Channel Catfish Production In PondsMichael Masser, Extension Fisheries Specialist

John Jensen, Extension Fisheries SpecialistJerry Crews, Extension Economist

C atfish farming has grown rapidly since its be-ginning in the 1960s. More than 18,000 acres ofwater were used in commercial catfish productionin Alabama in 1990. In the United States, catfishfarming is the largest aquacultural industry, withmore than 150,000 acres of water used to producean estimated 425 million pounds of farm-raised cat-fish in 1989.

Much of the total U.S. commercial production issold to catfish processors. Some producers sell liveor dressed catfish through local outlets. Many grow-ers stock their ponds for commercial recreationalfishing, and others sell their catfish to live-fish haul-ers who deliver primarily to recreational fishinglakes.

Catfish are grown in ponds, cages, and raceways.However, pond culture is by far the most commonmethod of production. Channel catfish require awarmwater environment for good growth. Optimumtemperature for growth is 85 °F. North Alabama hasabout 200 days per year when water temperatureis above 60 °F, while extreme South Alabama mayhave 250 days. All regions of Alabama are suitablefor commercial catfish production. Other factors be-ing equal, a greater annual production and returnon investment will be achieved with a longer grow-ing season.

The future for catfish farming in Alabama ap-pears bright. Catfish producers do encounter somedifficulties, including uncertain markets, “off-flavor,”water quality control, bird predation, harvestingdifficulties, and disease control. Still, the risks arenot much different from those encountered in otherfarm crops, and the industry continues to expand.However, management requirements are higher for

catfish production than for most other crop orlivestock enterprises. This publication briefly outlinesthe basic requirements for successful catfish farm-ing in Alabama.

Production EconomicsIs the catfish business something that could prove

to be a wise investment decision? Even if one hasa keen interest in producing catfish, could a higherreturn be earned by investing in some other venture?

To arrive at such a decision, the prospectiveproducer should make an economic evaluation of theproposed investment. The catfish operation shouldbe analyzed separately from the other farming oper-ations to determine its profitability. If the estimatesof yearly costs and returns are promising, theproducer should perform a whole-farm analysis tomeasure the impact of incorporating a catfish oper-ation into the farm business.

The economic feasibility of catfish productionshould reflect the producer’s own situation andresources. Making a realistic evaluation on paper willimprove your chances of success once money is com-mitted and will also reduce the possibility of un-pleasant surprises.

Investment RequirementsBefore the first fish is harvested, many invest-

ment items must be committed for efficient produc-tion. Listed below are items which may be requiredin many catfish operations:

Land TractorPond construction MowerDrain pipe and fittings Oxygen meterWells Water testing equipmentWater pumps and pipe SeinesElectric power lines Dip netsAerators (electric and/or Feed wagon/blowerPTO) Waders and boots

Boat and motor Baskets and bucketsHauling tanks and Storage buildings

agitators MiscellaneousTruck equipmentFeed storage bins

Enterprise BudgetingEstimating the costs and returns for a particular

activity is called developing an enterprise budg-et. This procedure reflects the economic value ofproducing a specific output using a given set of in-puts by following specific production practices.Profitability can be estimated by subtracting all thecosts from the expected revenues.

There are two types of costs to be considered indeveloping enterprise budgets: variable and fixed.Variable costs are the expenses that vary based onproduction output, such as feed, fingerlings, etc.Fixed costs are the expenses that do not change,regardless of whether production occurs: expensessuch as depreciation, interest on investment, in-

surance, taxes, etc. As in many other agricultural en-terprises, variable costs make up the largest portionof the total costs of catfish production. (See Figure1.) In an examination of variable costs alone, feedcomprises almost two-thirds of the costs, with fin-gerlings coming in a distant second, as shown inFigure 2.

Variable (83%)

Fixed (17%)

Figure 1. Breakdown of total costs for a catfishoperation.

Feed (64%)

Other (3%)Repairs (3%)Interest (4%)Electricity (5% )Chemicals (6%)Fingerlings (15%)

Figure 2. Breakdown of variable costs for a cat-fish operation.

Detailed enterprise budget estimates are deve-loped annually for various catfish production systemsand are available from your county Extension office.An example budget is shown in Figure 3.

Catfish Budget (Open Pond); Stocking In Spring, Custom Harvest In Fall;Estimated Annual Costs/ Returns; Using Recommended Management Practices;3,500 Fish Stocked Per Acre; 20 Lb./l,000 Beginning Weight; 2 Lb. Of Feed/Lb. Of Gain;200 Days In Growing Season; 1 Lb. Ending Weight; 7.25% Death Loss/Unharvested Fish.

Enterprise Acreage = 10

WeightItem Each

1. Gross ReceiptsCatfish 1.00

2. Variable CostFingerl ings (4-inch),Floating Feed (32%)ChemicalsHarvest LaborTractor (Fuel, Oil, Lube)ElectricityMiscellaneousMachine & Equipment (Repair)Interest On Operating Capital

Total Variable Cost

UnitPrice Or

QuantityValue Or

Cost/Unit cost

Lbs. 32,463.OO 0.65 21,100.95

EachTon

Appl. /AcreHr.Hr.

KWHAcreDol.Dol .

35,000.00 0.07 2,450.OO34.68 250.00 8,670.70

1.00 100.00 1,000.0032.00 4.00 128.0082.00 2.25 184.50

10,800.OO10.00

5,155.48

0.07 756.005.00 50.00

358.280.12 618.66

14,216.14

3. Income Above Variable Cost 6,884.81

4. Fixed CostInterest On Building

And EquipmentDepreciation On Building

And EquipmentOther Fixed Charges On

Building And Equipment

Total Fixed Costs

Dol .

Dol .

Dol .

9,424.50 0.12 1,130.94

1583.10

133.30

5. Total Of All Specified Expenses

6. Net Returns Above AllSpecif ied Expenses

2,947.34

17,163.48

3,937.47

Net Returns Per Acre: Above Specified Variable ExpensesAbove Specified Total Expenses

688.48393.75

Break-even Price (Per Cwt. Sold): To Cover Specified Variable ExpensesTo Cover Specified Total Expenses

Net returns are to land, existing pond, operator’s labor and management.These estimates should be used as guides for planning purposes only.

43.7952.87

Figure 3. A sample enterprise budget for catfish production.

This sample budget was developed for a hypo-thetical producer who has an existing lo-acre pond.The pond is stocked with 3,500 4-inch fingerlingsper acre of pond surface in the spring. Using a feedconversion ratio of 2:1 (pounds of feed per pound ofgain), the fish will be custom-harvested in the fallat an average weight of 1 pound. Efficiency factorssuch as feed conversion, death loss, and disease(chemical) costs are typical of a new operation. Asthe producer gains experience, efficiency in theseareas should improve by 25 percent or more, there-by reducing production costs.

Given the input costs and an expected sellingprice of 65 cents per pound, the net returns, orprofit, per acre will be $688 above variable (cash)costs, or $394 above total costs. Or, from a break-even standpoint, it will take 44 cents per pound tocover variable costs and 53 cents per pound to covertotal costs.

It must be remembered that, for this samplebudget, the net return estimate is to land, existingpond, and the operator’s labor and management.This means that these resources have not been ac-counted for. If a prospective producer does not havesuitable land or a suitable pond, these costs shouldbe added to the estimate and could increase the costof production by 5 to 10 cents per pound. Likewise,if the producer must hire a manager, this cost willalso substantially increase the break-even price.

Each producer will face a different situation whentrying to analyze the economic feasibility of catfishproduction. So, the budget estimates shown hereshould be used only as a starting point in the plan-ning process.Cash Flow Statement

In addition to budget analysis, the prospectiveproducer should also develop a cash flow statement.This prediction, or projection, reflects all cash inflowsand outflows on a monthly and/or yearly basis.Projections of cash surpluses and shortages can as-sist the producer in making credit arrangements andin determining his or her ability to repay loans.Whole-farm cash flow projections are helpful if ad-ditional money is needed to supplement the catfishoperation during the start-up period.

Cash flow projections should be estimated for 2to 3 years to get a more accurate indication of pay-

? .

back potential. More information can be found in Ex-tension publications ANR-355 and 355A, “Prepar-ing and Using the Cash Flow Statement.”

Sensitivity Analyses Of PriceAnd Production Factors

As with any business, it is important that goodmanagers pay close attention to those factors whichaffect profits most. Table 1 (below) summarizes thesensitivity of major price and production efficiencyfactors and their effect on profit potential. For ex-ample, for every tenth of a pound that the feed con-version rate can be lowered, the cost of productionwould decrease by $1.69 for every 100 pounds of cat-fish produced.

Table 1. Sensitivity Of Price And Production Fac-tors and Their Impact on Profits for a 10-AcrePond.*

ItemUnit Dollars Per

Change Cwt. SoldPond Construction $100/ac. 0.42Death Loss 1% 0.41Stocking Rate 500/ac

0.1 lb.2.57

Feed Conversion 1.69Feed Price $25/ton 2.24Interest Rate 1 point 0.44Fingerlings 1 cent each 1.13* Assumes starting with 4-inch fingerlings and a selling weight of1 pound.

Catfish production requires a great deal of moneyThe overall net worth and cash flow of the potentialproducer should be large enough to withstand boththe start-up period and any unforeseen setbacks. Anaverage producer may invest as much as $4,500 to$5,000 per acre before the first fish is harvested:$1,500 in operating costs; $1,500 to $2,000 inmachinery and equipment; and $1,000 to $2,000 inpond construction.

Successful catfish producers are both goodmanagers and good merchandisers. While catfishproduction has been successful for many producers,someone interested in the business would benefit byfollowing this advice:l Gain knowledge. Gather all the information youcan, even before you make your investment.l Plan. Lay a firm groundwork for financing, pro-

duction, and marketing before the business begins.l Start small. Limit your investment of time andmoney to minimize the risk for yourself and yourfarm.l Grow with success.

Pond ConstructionThe site and design of the pond may be the most

important factors controlling the profitability of thecatfish farm. Ponds that leak, have irregular bottoms,or routinely suffer from a shortage of water will notproduce a consistent crop of catfish.

Ideally, levee ponds built on flat land and filledwith groundwater or surface water are more suita-ble for commercial catfish production. However, mostAlabama terrain is rolling and not conducive to thiskind of construction. Also, water supplies for fillinglevee ponds are often scarce and will eventually limitthe use of the ponds. In hilly terrain, pond buildersmust take advantage of the natural formations byconstructing dams across valleys between hillsidesso that runoff from rainfall on the watershed will bestored behind the dam.

Water SuppliesWater to fill and maintain watershed ponds usual-

ly comes entirely from runoff, although groundwater(wells) and surface water (springs, streams, and reser-voirs) can also be used as supplemental sources. Theratio of watershed to water surface acreage shouldbe large enough so that ponds fill and sometimesoverflow during rainy months but drop no more than2 feet during drier months. The best ratio ofwatershed to water surface varies according to thetype of land on which the pond is built. For awatershed of heavy clay soil on open land, the bestratio is 5 acres of land for each surface acre of pond.For a sandy watershed in a wooded area, the bestratio is 30 acres or more of land for each surface acreof pond.

When a watershed is too small and unable to sup-ply enough water to the pond, or an outside sourceof water is needed for filling during dry periods,water from wells, streams, or rivers can be pumpedinto the pond. Water containing wild fish should befiltered to avoid introducing these fish into your pond.

When ponds are built in series in a valley, lesswatershed is needed to maintain an acre of water.Before harvest, water can be pumped or drainedfrom one pond to another for storage. This proce-dure not only allows a producer to refill, using thestored water, immediately after harvest, but it alsoeliminates the possibility of draining nutrients intonearby natural waters.

Soil CharacteristicsGood-quality soil that is at least 20 percent clay

is necessary for building the core of dams. This in-cludes clay, silty clay, and sandy clay soils. Soil shouldbe sampled by frequent borings along a proposeddam site to determine if the clay foundation is largeenough to build the dam.

Borings should also be taken from the proposeddam site and the shoreline to be sure there is enoughclay to build the dam. Usually a good source of claycan be found in the hillside near the dam site. If sucha source is available, using it to build the dam canadd to the size of the pond. However, if removing

the clay will uncover rock formations, sand, or gravelin the pond bottom, it is best to leave the clay inplace.

Pond construction in limestone areas can be es-pecially risky because of the possibility of underlyingcracks and sinks which may cause the pond to leak.In areas where the soil of the proposed pond bot-tom could result in leaky ponds, soils should be boredto check for quality. Approximately four borings peracre are sufficient, unless there are variations in soiltype in the pond bottom. Figure 4 shows the partsof a dam, including the core and drainage system.

TopographyTopography will greatly affect the size and shape

of a watershed pond. Generally, steep slopes in V-shaped valleys require dams of larger volume perwater surface acre than sites with gently sloping hillsand wide, flat valleys. So, ponds built in steep ter-rain usually cost more per pond acre than those builtin gently rolling terrain.

Figure 4. Cross-section of a typical dam at the drain pipe.

Ideally, watershed ponds should be less than 10feet deep at the drain. This depth allows theproducer to harvest the pond without draining it.Deep ponds must be drained of much of their waterbefore they can be seined for a complete harvest.

Some sites with gentle slopes and large flood-plains allow for the construction of two-sided andthree-sided watershed ponds (Figure 5). These pondsare usually constructed parallel to hills bordering acreek. Runoff is used as a water source, but the damdoes not cross a hollow or draw. The great advan-tage of this kind of pond is that it is a “seine-through”pond: it does not have to be drained for harvest.

Figure 5. Diagram of conventional hill ponds.

Other ConsiderationsThe site for a watershed pond should be select-

ed so that pipes and valves can be installed to drainthe pond completely. The proposed shoreline shouldbe excavated to provide a depth of at least 3 feetaround the edge of the pond. Pond bottoms shouldbe smooth and slope gently to the drain pipe.Remember, a poorly constructed pond with an un-even bottom will cause incomplete harvests.

Make sure that floods from nearby rivers will notflow over the dam or that floods within thewatershed will not weaken the dam. Ponds construct-ed in flood plains should be located so they will notcause damage to adjacent property if flooding doesoccur. Information on floods and their 100-yearpotential is available from the U.S.D.A. Soil Conser-vation Service field office in each county.

After deciding on a dam site, mark off the per-manent waterline and the potential flood-stage water-line of the proposed pond to make sure that waterwill not encroach on other property. Also, if the pondsite contains 1 acre or more of wetland, the U.S.Army Corps of Engineers will require a permit be-fore the pond can be constructed.

$2,500

$ 0 I5 10 15 20 25acres #-@-- one-sided 8 to

++a- one-sided 10 to+M+ two-sided 8 to 1- two-sided 10 to- three-sided 7 to

3010 ft.12 ft.0 ft.12 ft.IO ft.

Figure 6. Comparison of estimated constructioncosts (per acre) for typical hill ponds.

Cost of ConstructionThe curves in Figure 6 were developed by the

Alabama Fish Farming Center for ponds built inWest Alabama. The curves are estimates for datagenerated during 1987 and 1988. Cost estimates in-clude clearing, earthfill, excavation, pipe and drain,concrete, seeding, and road gravel. The term “sided”refers to number of sides of the dam. The measure-ments (such as "8 to 10 feet”) refer to the maximumdepth of water at the stand pipe. Each pond site isunique, and these curves should be used only forrough estimates and comparisons. In general, a large,shallow, one-sided watershed pond is relatively in-expensive to construct in West Alabama. A three-sided pond may cost about twice as much as a one-sided pond.

Building The PondTo obtain expert assistance in building the right

pond for your needs, contact the Soil ConservationService (SCS) field office in your county. The SCSprovides site evaluations, design layout, and construc-tion assistance.

Additional information on the construction of alevee pond can be found in the Southern RegionalAquaculture Center Publication No. 101, “Construc-tion of Levee-type Ponds for Fish Production.” SRACpublications are available from your county Exten-sion agent or from the Extension fisheries specialistsat Auburn University.

Stocking The PondSeveral species of catfish can be grown commer-

cially. They are the channel, the blue, and the whitecatfishes. The channel catfish is the one most com-monly used because it has the best combination ofcharacteristics for commercial production. The num-ber of fish to stock in a pond depends on severalfactors:l The size of the pond.l The experience of the producer.l The length of the growing season.l The desired market size.

The most important of these factors is the sizeof the pond. Fish should be stocked according to the

surface area of the pond. Overestimating the arearesults in more fish per acre than can be safely grown.Depth plays no part in determining stocking rate.

Experienced producers can stock up to 6,000 fishper acre, to produce 6,000 pounds per acre per year.Inexperienced producers should stock no more than3,500 fish per acre. A lower stocking density reducesthe risk of losses to oxygen shortages and diseases.In time, a new producer will gain the managementexperience that allows higher stocking rates.

Fingerlings can be stocked at any time during theyear. The best time to transport fingerlings is whenthe water is cool, so that stress on the fish is reduced.Fingerlings are trained to accept feed faster whentemperatures begin to moderate, usually duringFebruary and March.

Wild FishBefore stocking, eliminate all wild fish, such as

bream, minnows, and bullheads, that might eat foodintended for the catfish. Wild fish can also carrydiseases.

If possible, eliminate wild fish from the water sup-ply. Saran screen with 40 meshes per centimeter canbe used to filter out unwanted fish and fish eggs. Sa-ran can be used as a sock to fit over the water sup-ply pipe, or it can be framed into a box when largeflows of water must be filtered (see Figure 7).

Figure 7. Saran sock.

Largemouth bass fingerlings can be stocked withthe catfish at a rate of 50 per acre. Bass will eat smallwild fish, preventing a rapid increase in their num-bers. Bass do not tolerate low oxygen as well as cat-fish. If the bass are larger than 1 pound, stock catfishfingerlings that are over 8 inches long so that the basswill not eat them.

If wild fish are already in your pond, drain it com-pletely and leave it dry for several weeks. Rotenone(5 percent wettable powder or liquid formulation) ap-plied to remaining pockets of water at more than 3parts per million (10 pounds per acre-foot) will elim-inate any fish. In warm weather, rotenone detoxifiesin 7 to 10 days. In winter, rotenone may remain toxicfor more than 30 days.

TemperingBefore stocking fish in a pond, adjust the water

in the transport tank holding the fingerlings to matchthe pond water in temperature and other water qual-ity factors such as pH, alkalinity, and hardness. Thiscan be done by putting small quantities of water intothe tank from the pond (called tempering), so that thetank water is eventually similar to that of the pond.

As a general rule, catfish can withstand a 5°Fchange in temperature without severe stress and a10 °F change if the water is tempered over a periodof 30 minutes. For greater temperature differences,care must be taken to slowly equalize water temper-atures before moving the fingerlings from the tankto the pond. In this case, adjusting water tempera-ture l°F every 10 minutes is a good rule to follow.Tempering is especially important if fish are goingfrom cool water to warm water.

Insufficient tempering can kill the fish by temper-ature shock or shock from other water quality fac-tors. If the fish are not killed by the shock, they canbe weakened, which lowers their resistance to disease.

Starting with good-quality, healthy fingerlings ofknown genetic background is very important toprofitably growing a crop of fish. Buy your finger-lings from a producer who has a reputation forproducing good fish, who knows how to treat fish fordisease, who has the equipment and the know-howto handle them without excessive stress, and whodelivers accurate counts and weights.

FeedingCatfish grown at high densities require a nutri-

tionally complete feed for good growth and health.Commercially prepared catfish feeds, available in bulkor in bags, should contain from 26- to 36-percentcrude protein plus all essential vitamins and miner-als to be called “complete.” Feeds containing32-percent crude protein are adequate and the mosteconomical for food fish production. Feeds of26-percent crude protein can be used for winter feed-ing and by people who produce small quantities ofcatfish for home use.

Both sinking (pelleted) or floating (extruded) feedcan be fed to catfish. Both types, if complete, giveadequate growth under normal conditions. Floatingfeeds are more expensive, but they allow the producerto observe feeding activity Feeding activity is ex-tremely important in determining how much to feed,and it is usually the best opportunity the producerhas to judge the health and vigor of the fish. A mix-ture of 15-percent floating and 85-perent sinking feedcan be used to cut costs and still allow observationof feeding activity.

Fish feeds come in various sizes. Crumbles(crushed pellets) can be fed when fingerlings are lessthan 3 inches long. Fish larger than 3 inches can befed a 3/16-inch pellet until they reach market size. Fishare usually fed out on 1/4-, 5/16-, or 3/8-inch pellets once they reach 1/2 pound in weight.

Feeding RatesOne of the biggest problems producers encoun-

ter is knowing how much to feed each day Overfeed-ing wastes feed and money, and it can causewater-quality problems. Catfish will grow at theirmaximum rate when fed all they will voluntarily eat(called “satiation”). However, trying to satiate the fishusually results in overfeeding.

Timed Feeding. Research has shown that cat-fish grow most efficiently when fed about 90 percentof all they will voluntarily eat. This optimum feedingrate is generally reached when catfish are fed onlythe amount they will eat in 5 to 10 minutes. It is im-portant that the fish eat as much as they want,without leaving any excess.

Feed Conversion Method. Another way to es-timate the amount to feed during summer months

is to calculate the total initial weight of the fish inthe pond and feed the percentage of body weightrecommended in Table 2 each day for a 2-week peri-od. Every 2 weeks, the weight gain can be estimat-ed based on the feed conversion ratio (FCR) and theration adjusted. The formulas for this procedure andan example computation are shown in Table 3.

In the example in Table 3, 185 pounds of feedwould be fed each day for the next 2 weeks. Thena new feeding rate would be calculated using thismethod. It should be pointed out that this methodis only as good as the ability to estimate the FCR.

Fish Sampling Method. A third method tocalculate feeding rates is to estimate the total weightof the fish based on the weight of a sample. Althoughresearch has shown that average sample weights canvary from 8 to 19 percent from true average weights,this method is still effective.

At 2-week intervals, the producer captures a sam-ple of 100 fish at random with a net (not hook andline) and weighs them. The producer can then

Table 2. Typical Feeding Schedule.”

Feed Weight ofallowance feed per

Date

per day- acre perWater Fish percent of day per

temperature size fish weight 1,000 fish“F lb. % lb.

4-15 6 8 0.04 2 .2 0 .94-30 7 2 0.06 2 .8 1.75-15 7 8 0 .11 3 .0 3 3

*5-30 8 0 0.16 3 .0 4:86-15 8 3 0.21 3 .0 6 .36-30 8 4 0.28 3 .0 8 47-15 8 5 0.35 3 .0 10.57-30 8 5 0.42 2 .8 11 .88-15 8 6 0.60 2 .4 14.48-30 8 6 0.75 2 .0 15.09-15 8 3 0.89 1.8 16.09-30 7 9 1 .01 1.6 16.0

IO-15 7 3 1 .10 1.2 13.2*For channel catfish in ponds, stocked with 5-inch fingerlings andharvested at 1.1 pounds.

calculate the next feeding rate by estimating the to-tal fish weight in the pond from this sample. Theformulas for these calculations and a sample estimateare shown in Table 4.

In the example in Table 4, 150 pounds of feedwould be fed each day for the next two weeks. Thena new feeding rate would be recalculated based onanother sample.

Using Table 2, the daily feed allowance, as a per-centage of body weight, can be estimated as fishgrow. Table 2 is a guide for feeding catfish duringthe spring, summer, and early fall growing seasons,beginning with fish newly stocked in April. Remem-ber, this table is only a guide and fish may responddifferently from day to day and from pond to pond.

Feeding less than 35 pounds of feed per acre ofpond per day will minimize low-oxygen problemscaused by high stocking densities and feeding rates.However, emergency aeration may be needed attimes during the summer, even at this feeding rate.If effective aeration equipment is available, feedingrates of up to 100 pounds of feed per acre per daycan be used. The majority of producers should tryto maintain feeding rates below 70 pounds of feedper acre per day to grow out large numbers of fishbut minimize risk.

Table 3. Feed Conversion Method.

Estimated weight gain =total pounds of feed fed x 0.556 (FCR = 1:1.8)New total fish weight in pond =estimated weight gain + last total fish weightNew daily feeding rate dnew total weight of fish x (percentage of body weightfrom Table 2)

Example: A 5-acre pond is stocked at 4,000 fish peracre, and the total fish weight is 5,000 pounds. Fortwo weeks, the fish are fed at 3 percent (150 poundsper day or 2,100 pounds per 2 weeks).

Est. wt. gain = 2,100 x 0.556 = 1,167.6 or 1,168 (lb.gain)New total fish wt. = 5,000 + 1,168 = 6,168

New daily feeding rate = 6,168 x 0.03 (from Table2) = 185.04 or 185 lb./day

Feeding ScheduleFeeding fish twice each day can be advantageous

when fish are less than 1/2 pound (usually Aprilthrough July). Twice-daily feedings should be at least6 hours apart to allow for digestion. When fed twicea day, catfish will eat and gain more than when theyare fed once a day

Catfish can be trained to eat at nearly any timeof day During the summer, it is not advisable to feedtoo early in the morning or after sundown, becauseof potential low-oxygen problems. Fish do not con-sume as much feed if oxygen is low, and the processof digestion increases oxygen uptake. Feeding around9:00 a.m. in the summer is a good practice if oxy-gen levels are good. Once a feeding time is estab-lished, maintain it. Catfish will feed better if a dailyroutine is followed. For the same reason, try to feedin the same location each day. However, you mayhave to change the feeding location to account forwind direction and velocity when you are using float-ing feed.

Feed catfish 7 days a week. They will grow lessquickly and efficiently if they are fed less often.Remember: no feed, no gain; no gain, no profit.

Catfish are naturally aggressive and attempt todominate each other over food. So, spread the feedout over a large area in the pond to allow smallerfish a better chance to feed. This practice will resultin a more uniform size at harvest. It is very impor-

Table 4. Fish Sampling Method.

Average weight of individual fish =weight of 100 fish + 100New total fish weight =average weight x number of fish in the pondNew daily feeding rate =new total fish weight x (percentage of body weightfrom Table 2)Example:A 5-acre pond is stocked at 4,000 fish per acre. A sam-ple of 100 fish weighs 25 pounds.

Ave. wt. of fish = 25 + 100 = 0.25 lb. per fishNew total fish wt. = 0.25 x 20,000 = 5,000 lb.New daily feeding rate = 5,000 x 0.03 (from Table2) = 150 lb. /day

tant to widely distribute feed across the surface oflarge ponds because of the large number of fish tobe fed.Winter Feeding

The growth of channel catfish slows during thewinter, but feeding at a lower rate is important.Without feed during the winter, catfish will loseweight and be less resistant to disease when the waterbegins to warm in the spring. Catfish do feed at lowtemperatures, just not as often.

A satisfactory winter feeding schedule for catfishin ponds is to feed about 1 percent of their bodyweight every other day when the water temperatureis between 5 5 ° and 65° F. Feed 1 percent of theirbody weight twice a week when the water tempera-ture is between 45 ° and 54 ° F. Feed in the afternoon,when the temperature is highest, and on sunny days.Many producers feed sinking pellets in winter, if thefish will not come to floating feed. More informationon winter feeding of catfish can be found in Exten-sion circular ANR-457, “Feeding Catfish DuringWinter?

Feed ConversionGood feed conversion depends on good manage-

ment. A producer who manages the catfish well canachieve feed conversions between 1.5 and 2 poundsof feed to 1 pound of fish gain. A producer can in-

crease profits by about 1 to 2 cents per pound of fishfor each tenth of a pound of improved feed conver-sion, depending on the price of feed (Table 5). Theopposite is true when management is poor.

Feed StorageStore feeds in a cool, dry place. Damp storage

areas (bins or rooms) can cause mold to grow on feeds.Heat causes loss of vitamins. Do not use feeds thathave been stored for more than 8 weeks during warmweather. Never use feeds that are moldy or clumpedtogether. Eating contaminated or vitamin-deficientfeed can slow growth, lower resistance to disease, andcause deformities or death.

Water QualityThe most serious threat to catfish in ponds is poor

water quality. Water quality is not constant. It varieswith the following factors:

l Time of day.l Season.l Weather conditions.l Water source.l Soil types.l Temperature.l Stocking density.l Feeding rate.l Chemical treatments.

Table 5. Cost Of Feed (In Cents*) To Produce A Pound Of Catfish At Various Feed Prices AndFeed Conversion Ratios (FCR).

Feed Price/ ton

FCR $230 $250 $270 $290 $ 3 1 0 $330 $350

I.3 1 5 . 0 16.3 17.6 18.9 20.2 21.5 22.81.4 16.1 17.5 18.9 20.3 21.7 23.1 24.51.5 17.3 18.8 20.3 21.8 23.3 24.8 26.31.6 18.4 20.0 21.6 23.2 24.8 26.4 28.01.7 19.6 21.3 23.0 24.7 26.4 28.1 29.81.8 20.7 22.5 24.3 26.1 27.9 29.7 31.5

'1.9 21.9 23.8 25.7 27.6 29.5 31.4 33.32.0 23.0 25.0 27.0 29.0 31.0 33.0 35.02.1 24.2 26.3 28.4 30.5 32.6 34.7 36.82.2 25.3 27.5 29.7 31.9 34.1 36.3 38.52.3 26.5 28.8 31.1 33.4 35.7 38.0 40.32.4 27.6 30.0 32.4 34.8 37.2 39.6 42.02.5 28.8 31.3 33.8 36.3 38.8 41.3 43.8

* rounded to the nearest tenth o f a cent

A successful catfish producer must understandpond dynamics, the effect of catfish production onwater quality, and management of water-qualityproblems.

Aspects of water quality of concern in catfishproduction include:

l Temperature.l Dissolved oxygen.l pH.l Ammonia. * Nitrite.l Alkalinity.l Hardness.0 Carbon dioxide.l Chloride.

Temperature does not change very rapidly exceptin the case of small, shallow ponds. Dissolved oxy-gen, pH, and carbon dioxide levels change or fluc-tuate daily Ammonia, nitrite, alkalinity, hardness,and chloride generally change slowly, although ex-ceptions do occur under extreme conditions. Rela-tively inexpensive and easy-to-use chemical tests areavailable for checking these water quality factors. Forinformation on how to order test kits, contact yourcounty Extension office or the Extension fisheriesspecialists.

Pond DynamicsNo two ponds are exactly alike. Pond color and

water quality vary within a single pond from day today. Adjacent ponds are seldom alike in their color,water quality, and the growth rate of the fish, eventhough they are stocked and fed at the same rates.These differences are not fully understood but maybe related to soil conditions, algae (microscopic plantscalled phytoplankton), and bacterial populations ofthe pond.

TemperatureWater temperature is one of the single most im-

portant factors in ponds. The metabolic rates of theplants, bacteria, and fish depend on the temperature.Catfish are warmwater fish and perform most effi-ciently at warm temperatures (approximately 80 ° to85 ° F). At higher temperatures, respiration rates arehigh, feed conversion is poor, and overall growth is

reduced. Channel catfish will die at temperaturesabove 96 °F.

Temperatures below the optimum range reducemetabolic rate, feed consumption, and growth. Verylow temperatures impair the immune system andlower resistance to disease. Rapid changes in tem-perature, especially during hauling and stocking,stress fish and may reduce feeding and increase sus-ceptibility to disease.

AlgaeAlgae are extremely important to catfish ponds.

Algae produce most of the oxygen in the pond andremove most of the carbon dioxide and many of thenutrients. Algae also consume oxygen, produce car-bon dioxide, cause pH to fluctuate, and releasenutrients into the water as they die.

Algae populations change continuously, becausedifferent species flourish at distinct temperatures andunder various pH and nutrient conditions. Algaepopulations, called “blooms,” can die off and resultin fish kills. The only way a fish farmer can becomean efficient producer is to continuously monitor andkeep records of bloom conditions, oxygen concentra-tion, and other water quality factors.

Dissolved OxygenLow dissolved oxygen is by far the most common

water-quality problem in catfish production ponds.Ponds get oxygen from two sources: the air and pho-tosynthesis. Oxygen diffuses into water from the air.Diffusion is a slow process unless it is aided by theaction of wind or some type of mechanical agitationthat mixes air and water together.

Most pond oxygen comes from photosynthesis.Photosynthesis is the process by which plants makefood from carbon dioxide, water, nutrients, and sun-light. The by-product of photosynthesis is oxygen.On sunny days, algae produce and release oxygen,which dissolves into the water. At night, no oxygenis produced and the respiration of the algae and fishand the decomposition of wastes by bacteria removeoxygen from the pond.

Under natural conditions, more oxygen is pro-duced by photosynthesis than is removed by respi-ration, as it cycles up and down during the day.Figure 8 shows a general oxygen cycle for ponds dur-ing warm weather conditions.

Midnight 6 a.m. noonTime Of Day

Figure 8. General 24-hour oxygen cycle in ponds.

9 p.m. Midnight

The amount of oxygen that will dissolve in waterdepends on the temperature, salinity, and atmospher-

Cold water holds or will dissolve more oxygenthan warm water. Therefore, as temperature in-

ic pressure. Salinity and atmospheric pressure areof little consequence in fresh water catfish produc-tion areas. Temperature, however, is an importantregulator of dissolved oxygen levels in ponds.

creases in the pond, less oxygen is available. Theamount of oxygen that water will dissolve at differ-ent temperatures (saturation) is listed in Table 6.

Table 6. Dissolved Oxygen Concentrations At Saturation For Different Temperatures.

Temperature, Dissolved Temperature, DissolvedDegrees Cl Oxygen, ppm Degrees Cl Oxygen, ppm0 (32) ................................ 14.60 18 (64) ................................. 9.451 (34) ............................... ..14.19 19 (66) ................................. 9.262 (36) ................................ 13.81

i3.4420 (68) ................................. 9.07

3 (37) ................................ 21 (70) ................................. 8.904 (39) ............. : .................. 13.09 22 (72) ............................... ..8.7 25 (41).................................12.7 5 23 (73) ............................... ..8.5 66 (43) ................................ 12.43 24 (75) ............................... ..8.4 07 M4).................................12.12 25 (77) ............................... ..8.2 48 (46).................................11.8 3 26 (78) ............................... ..8.0 99 (48L................................l1.5 5 27 (80) ................................. 7.9510 (50).................................11.2 7 28 (82) ................................. 7.8111 (52). .............................. ..ll.O 1 29 (84) ............................... ..7.6 712 (53).................................10.7 6 30 (86) ............................... ..7 5413 (55).................................10.5 2 31 (88) ................................. 7.4114 (57).................................10.2 9 32 (90) ............................... ..7.2 815 (59) ............................... ..lO.O 7 33 (92)..................................7.1616 (61) ................................. 9.95 34 (93) ................................. 7.0517 (62) ................................ 9.65 35 (95) ................................. 6.93‘Numbers in parentheses are degrees F.

The amount of oxygen that dissolves in water isvery small compared to the oxygen concentration ofthe atmosphere. The atmosphere contains about 20percent oxygen, or 200,000 ppm (parts per million).Water at saturation at 85 °F contains less than 8 ppmoxygen. Ponds can supersaturate with oxygen on sun-ny days when algae in the pond are very dense (heavybloom). Very high concentrations of oxygen (twicesaturation) during the day sometimes indicate that anoxygen depletion will occur that night.

Critically low dissolved oxygen concentrations canusually be predicted. Low levels occur because of oneof the following:

l Extremely high oxygen demands, due to highnighttime respiration caused by very dense algaeblooms plus fish and waste decomposition.

l Excessive decomposition from algae bloomdie-offs.

l Turn-overs related to weather changes such asrain, wind and cold air.

l Reduced oxygen production from photosynthe-sis due to reduced sunlight from cloud cover, fog, orhaze.

l Lack of agitation from wind.l Rapid reduction in ‘algae population from

die-offs.Most low-oxygen problems occur between May

and September. During this period, temperatures arewarm, feeding rates are high, algae blooms are heavy,and fish are growing rapidly. All of these conditionscan cause more oxygen to be removed from the pondat night than is produced during the day Also, stilland overcast days may reduce the amount of oxygenproduced by wave action and by photosynthesis. Thiscondition may promote an oxygen depletion. Theresult can be dead fish.

An oxygen depletion can also be caused by whatis called a “turn-over.” In the summer, the surface ofthe pond heats up rapidly, forming a warm and lessdense layer of water. This warm layer traps a cooler,denser layer of water beneath it. The pond is saidto be “stratified” in this condition.

The two water layers do not mix with each otherunder normal conditions because of their differingdensities. Oxygen is only produced in the upper warmlayer and slowly becomes depleted in the lower layerbecause of bacterial and chemical action.

A cool front or a thunderstorm with wind and coldrain can cool the surface of the pond enough to makethe two layers mix. The result is the dilution of theoxygen that was in the upper layer and an increasein demand for oxygen. The increased demand isusually both biological and chemical.

The algae usually die off under these conditions,causing rapid oxygen removal through bacterialdecomposition. Turn-overs are a common cause ofcatastrophic fish kills in deep ponds (more than 8feet)

Oxygen concentrations should be maintainedabove 4 ppm at all times if catfish are to grow well.Growth can be severely affected when oxygen levelsremain below 4 ppm for extended periods. Stresscaused by chronically low oxygen will lower resistanceto disease.

Predicting Low OxygenMonitoring and predicting low oxygen is critical.

Dissolved oxygen can be measured using either elec-tronic or chemical methods. Electronic oxygen metersare relatively expensive but have become standardequipment on commercial catfish operations (Figure9). Electronic oxygen meters require maintenance andcalibration, but they are quick and accurate. Chemi-cal dissolved-oxygen tests are accurate if directionsare precisely followed, but they take several minutesto complete. For this reason, chemical tests are notrecommended if more than three ponds are to be test-ed. Accurately reading color changes of the chemicalmethod is difficult at night in poor light.

Figure 9. Electronic oxygen meter.

Graphic Projection Method. Low dissolved oxy-gen can usually be predicted using the graphic projec-tion method. This method relies on the fact thatoxygen generally declines at a constant rate through-out the night. Based on this steady decline, low oxy-gen can be predicted by graphing the rate of declineand projecting this decline until morning. To use thismethod, oxygen readings must be taken near duskand 2 to 4 hours later.

To use this method, mark graph paper as shownin Figure 10, with oxygen concentrations along theY axis (vertical). Mark time along the X axis (horizon-tal). Next, mark the two oxygen readings on the graphand draw a straight line through them to the X axis.If this line indicates that the oxygen concentrationswill fall below 3 ppm before sunrise, then aerationwill probably be necessary.

One word of caution: this method onlypredicts low oxygen and gives the manager timeto take appropriate action. It is not foolproof and stillrequires that oxygen be monitored to prevent unan-ticipated problems.

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8 9 1 0 1 1 1 2 1 2 3 4 5 6

P*m. Time Of Nighta.m.

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8 9 10 11 12 1 2 3 4 5 6

P*m’ Time Of Nighta.m.

Figure 10. Graphic method of predicting oxygendepletions.

In Pond 1, the dissolved oxygen concentration at8:00 p.m. is 12 ppm, and at lo:30 p.m. it is 6 ppm.Drawing a line through these two points indicatesthat the oxygen concentration will fall below 4 ppmbetween 11:00 and 11:30 p.m. Emergency aerationshould begin before midnight.

In Pond 2, the dissolved oxygen concentration at8:00 p.m. is 10.5 ppm, and at 11:00 p.m. it is 8.5ppm. Drawing a line through these two points indi-cates that oxygen concentration will not fall below4 ppm by sunrise. In this case, emergency aerationis probably not necessary.Pond Record Method. Another method topredict low oxygen was developed from analyzingactual fish farm records. These records show that,if the oxygen concentration at dawn is 5 ppm or moreand at dusk is the same as or greater than the daybefore at dusk, then no oxygen depletion will occurthe upcoming night. But, if the oxygen concentra-tion is less than 5 ppm and is less at dusk than itwas the day before, then an oxygen depletion canbe expected during the coming night. Figure 11shows a sample graphic pond record which predictsthat a nighttime oxygen depletion will occur.

14

12

10

8

6

2

0

6 a . m . 6 p . m . 6a.m. 6 p . m . 6 a . m . 6 p . m . 6a.m.

S u n . Mon. Tues. W e d .

Figure 11. Graphic pond record predicting thata nighttime oxygen depletion will occur becausethe oxygen concentration is less than 5 ppm atdawn and was less at dusk than the day before.

Successful pond managers monitor oxygen everyday at daybreak, at nightfall, and during the nightthroughout the growing season. Decreasing morn-ing oxygen levels from day to day, low evening read-ings, and increasing supersaturation levels usuallywarn of upcoming problems. It is important to takereadings at the same time and at the same locationeach day. In ponds larger than 5 acres, oxygen read-ings should be taken at two ends of the pond be-cause oxygen may vary widely in the same pond.Keeping a chart (Figure 12) of daily oxygen read-ings will help you predict developing problems. Donot rely on memory. Maintain good recordsand use them.

I I I I I I I I I I I I I I IiAM PM AM PM AM PM AM PM AM PM AM PM AM PM AM PM AM

Figure 12. Chart of daily oxygen readings.

AerationCommercial production in high-density catfish

ponds requires aeration. Aeration strategies can bedescribed as supplemental or emergency.

Supplemental aeration involves the nightly oper-ation of aerators, regardless of the dissolved oxygenlevel, in an attempt to maintain oxygen concentra-tions above stressful levels. In supplemental aeration,aerators are run 5 to 7 hours per night beginningabout midnight and ending about dawn.

Supplemental aeration appears to increase feedefficiency and total pounds of catfish produced overemergency aeration at moderate stocking and feed-ing rates (4,000 fish per acre and a maximum feed-ing rate of 50 pounds per acre per day). As stockingand feeding rates increase, supplemental aerationmay not increase production.

Emergency aeration is used when the dissolvedoxygen concentration drops to critical levels, whenfish may die if not assisted. Emergency aeratorsmust be available when using supplemental aeration.

Once emergency aeration is begun, it should con-tinue until the oxygen level is above 4 ppm and thefish no longer gasp at the surface for air. This usuallyoccurs after an extended period of aeration, after sun-rise when photosynthesis begins, or when overcastcloud conditions break up during daylight.

AeratorsMany types of aerators are commercially availa-

ble. Aerators can be powered by electricity, diesel en-gines, or the power-take-off (PTO) of a farm tractor.The efficiency of an aerator can be determined fromits ability to transfer oxygen into water. Aerators arerated in terms of pounds of oxygen transferred perhorsepower per hour.

Most producers prefer stationary electrical aera-tors used for supplemental aeration. Electrical aera-tors are usually more efficient and less expensive tooperate and maintain. As a general rule, 1 to 1 1/2horsepower per surface acre is sufficient capacity forsupplemental aeration and for some emergencies, ex-cept in extreme cases such as a bloom die-off.

In extreme cases, portable emergency aerators,like PTO-driven paddlewheels, are needed in addi-tion to whatever stationary aerators are already inthe pond.

Both electrical-paddlewheel (Figure 13) andpump-sprayer aerators are efficient and effectiveemergency aeration devices for use in ponds. Bothagitate the water and create a current. The movingwater rapidly saturates with oxygen and the current(or waves) increases the absorption of oxygen acrossthe-surface of the pond. The current is also impor-tant in attracting fish to the aerated zone. Padd-lewheels and pump sprayers can be powered byPTO's, electricity, or diesel engines.

Figure 13. Electric paddlewheel.

Spray- or vertical-pump surface aerators that liftwater (Figure 14) are usually not as efficient as padd-lewheels or pump sprayers in emergency situations.However, they may be useful in small ponds in main-taining acceptable oxygen concentrations.

Figure 14. Surface aerator.

Propeller-aspirator pump aerators have high-speed propellers equipped with hollow drive shafts.As the propeller turns, it causes air to be drawn downthe shaft and mixed into the water. These are notas effective as paddlewheel aerators, but they offerthe added benefit of helping to destratify (break uptemperature layers) deeper ponds. However, to des-

i1

tratify ponds effectively, they must be operated con-tinuously Propeller-aspirator pump aerators come

in many sizes and, therefore, may be adapted to smallponds.

Diffuser aerators are operated by compressors orair blowers that release bubbles of air into the water.Diffusers are not very effective in most commercialcatfish ponds.

Motorboats, twisting and turning at high speeds,have also been used for aeration in ponds. Large,tractor-powered rotary mowers, placed so that themower blades agitate the surface water, have beenused as well. However, the effectiveness of thesemethods is limited.

More detailed information on aerators and theirefficiency can be found in Experiment Station Bulle-tin 584, “Evaluation of Aerators for Channel CatfishFarming,” available from the Alabama AgriculturalExperiment Station at Auburn University.

Placement of AeratorsStationary aerators should be placed where they

will create the maximum circulation in the pond. Inrectangular ponds, place stationary aerators in thecenter of the longest levee or side, with the dischargetoward the middle of the pond. In this position, wateris directed perpendicularly to the longest side andmoves across the pond to create currents that reachmost areas of the pond.

Placing aerators in the comer of the pond todirect water diagonally across the pond producespoor circulation. Locating fixed aerators in the mid-dle of the levee will cause higher installation costsand may be inconvenient when aeration is neededat another location for harvesting operations. Porta-ble aerators can be used during harvest.

Most aerators will not deliver adequate oxygenthroughout the pond but will create oxygen-richareas to which fish will be attracted and in whichthey can survive. Portable emergency aerators shouldbe used before fish are stressed to the point that theycannot reach the aerated area. The best placementfor an emergency aerator is in the area of the pondwith the highest oxygen concentration. Fish will begathered in this area.

If two aerators are needed, place them near eachother (30 to 50 feet apart). This way, if one aeratorfails, the other can hold the fish in the area and keepthem alive until the problem is fixed. In single-

aerator situations, if the aerator fails, the fish willmove into oxygen-poor areas in search of more oxy-gen. At that point, during a severe oxygen depletion,the fish may be dead by the time additional aera-tion is moved to the pond.

Fish cover the surface of the pond, particularlyalong the banks, when they are severely stressedfrom low oxygen. Place aerators in the areas wherethe most fish are congregated and try to attract themto the aerator. In a hill-type pond, fish will usuallygo to the shallow end in search of higher oxygen.Be prepared to operate an aerator in shallow water.Bankwasher aerators are effective at quickly provid-ing oxygen to fish along the shoreline.

Most producers do not have enough paddlewheelor pump sprayer aerators for all ponds and, there-fore, move them to ponds as they are needed. Oneportable aerator for every three to four ponds is ade-quate. If aeration requirements exceed the oxygensupplied by available equipment, then the ponds withthe fastest-falling oxygen levels or the most valua-ble fish should be aerated first.

A portable paddlewheel or pump sprayer aera-tor can be difficult to situate in a pond properlywithout damaging it or the tractor. Before emergen-cies arise, try running aerators in several probablelocations around each pond, so that placement be-comes more or less routine. This is particularly im-portant because most aerator maneuvering is doneat night.Common Aeration PracticesAnd Designs

This section briefly describes some commonmethods of aeration. Additional information can befound in Southern Regional Aquaculture Center Pub-lication No. 370, “Pond Aeration” and SRAC Publi-cation No. 371, “Pond Aeration: Types and Uses ofAeration Equipment.” These publications can be ob-tained from your county Extension agent or from theExtension fisheries specialists.Well water. Pumping water from a well, stream,or adjacent pond with a high oxygen content is agood way to aerate in an emergency. Well water isoften low in oxygen and must be splashed or sprayedbefore it enters the pond.

If well water is not available or not in sufficientquantity, then water from an adjacent pond or stream

may be a good substitute. Water from streams orother ponds is not as desirable as well water, becauseit can be a source of wild fish and disease.

To aerate ponds in this way, you need equipmentthat will pump at least 100 gallons per minute foreach acre of pond. Drain some water from the pondbottom while adding water at the surface. Thismethod is more effective than allowing excess sur-face water to pass through the pond standpipe orspillway.Spraying. Water from the pond low in oxygen canbe sprayed into the air to add oxygen. Place pumpintakes just beneath the surface, not on the pond bot-tom. Discharge the water just a few feet above thesurface of the receiving pond.

A pump sprayer or relift pump powered by thePTO of a farm tractor (Figure 15) is an-effective aer-ator for this situation. The discharge can be cappedand slots cut in the sides to increase efficiency.Another modification is to mount the dischargemanifold parallel to the surface of the pond and dis-charge in opposite directions down the pond bank(called a “bank washer”). PTO-, electric-, and dieselengine-powered pump sprayers are commerciallyavailable.

Figure 15. A pump-sprayer powered by a farmtractor.

Claims that chemicals such as potassium perman-ganate and phosphate fertilizers alleviate oxygenproblems are unfounded.

Carbon DioxideThe same factors that produce low dissolved oxy-

gen concentrations in ponds also contribute to highcarbon dioxide (CO2) concentrations. Carbon diox-ide increases through the night because of respira-tion. Carbon dioxide levels can also increase rapidlyafter an algae bloom die-off.

Carbon dioxide interferes with oxygen uptake atthe gills, so fish will show signs of oxygen stress eventhough oxygen readings may be in a safe range. Aconcentration of over 25 ppm of carbon dioxide inpond water is generally harmful to catfish and maycause death.

Aeration is the best way to help rid the pond ofcarbon dioxide and increase oxygen levels. Up to 100pounds per acre of hydrated lime, Ca(OH)2, may beadded in extreme cases to remove some of the CO2.

pHThe pH is a scale on which the acidity (hydro-

gen ions) and alkalinity (hydroxide ions) of water ismeasured. A pH of 7 is neutral (balanced in H + andOH - ions). Changes in the pH of a pond occur dur-ing a 24-hour cycle because of respiration.

Carbon dioxide from nighttime respiration reactswith water to form carbonic acid. Carbonic aciddrives pH downward, making the water more acid-ic. During the daytime, pH moves upward (the waterbecomes more alkaline) because the carbon dioxideis removed for photosynthesis.

The optimum pH for catfish ponds is between6.5 and 8.5. But in production ponds, pH can varyfrom 6.0 to 9.5 without severely stressing the fish.

The pH of the pond is usually checked only be-fore certain chemicals are added or if ammonia lev-els are high. The pH of the pond affects the toxicityof chemicals like copper and ammonia. The pH ofthe pond water is strongly influenced by the pH ofthe pond mud and of the soils in the watershed.

The only way to modify pH in ponds is by ad-ding lime, gypsum, alum, or bicarbonate. However,adding chemicals to alter pH should be done onlyin extreme circumstances.

Alkalinity And HardnessAlkalinity is a measure of bases in water. These

bases include hydroxides (OH - ), carbonates(CO3 -2), and bicarbonates (HCO3 - ). They are relat-

ed to, but not the same, as pH. Alkalinity acts asa buffer to absorb hydrogen ions and resist pHchanges.

Hardness is a measure of divalent (+2) ions,mostly calcium and magnesium. In chemical tests,both are measured in ppm of calcium carbonateequivalence, which leads many people to think thatthey are the same.

If alkalinity and hardness are both derived fromlimestone soils, then they usually have similar values.It is possible, however, to have water that is high inalkalinity and low in hardness and vice versa.

Alkalinity and hardness should be maintainedabove 20 ppm. Alkalinity can be increased by ad-ding agricultural limestone, hydrated lime, quicklime, sodium bicarbonate, or sodium hydroxide.Generally agricultural lime is the least expensive andmost predictable chemical to adjust alkalinity.

More information on this use of agricultural limecan be found in Extension circular ANR-232, “Lim-ing Fish Ponds.” This publication is available fromyour county Extension agent or from the Extensionfisheries specialists at Auburn University.

Alkalinity affects the toxicity of copper treat-ments in ponds. A fish farmer should check alkalin-ity before determining the rate for applying coppercompounds. More information is found in Extensioncircular ANR-414, “Tables For Applying CommonFishpond Chemicals,” available from your county Ex-tension agent or the Extension fisheries specialists.

Hardness can also be increased by the additionof agricultural limestone, hydrated lime, quick lime,gypsum, or calcium chloride. Low hardness can bea problem in catfish hatcheries. Hardness of hatch-ery water (pond or well) should be checked beforethe spawning season.

Nitrogen WastesCatfish, like all other animals, produce nitro-

genous wastes from the digestion of the proteins intheir diet. Ammonia is the principal nitrogen wasteproduct. It is excreted directly into the water fromthe gills and kidneys of the fish.

Ammonia is also produced from bacterial decom-position of the proteins from uneaten feed and fromany dead animal or plant, including algae. About 2.2pounds of ammonia is produced from each 100pounds of feed fed.

Ammonia, once released into the pond, can beabsorbed by algae or bacteria. Algae use ammoniaas a nutrient for growth and reproduction. Certainaerobic (oxygen-requiring) bacteria use ammonia asa food source in a process called “nitrification.”

Nitrification is an important process by which tox-ic nitrogenous wastes are decomposed. In the processof nitrification, bacteria of the genus Nitrosomonasconvert (oxidize) ammonia to nitrite, and bacteriaof the genus Nitrobacter convert nitrite to nitrate.Ammonia and nitrite are both toxic to fish; nitrateis not.

Ammonia Toxicity. Ammonia in water dis-solves into two compounds: ionized (NH4 + ) and un-ionized (NH3) ammonia. Un-ionized ammonia is ex-tremely toxic to catfish, while ionized ammonia isrelatively nontoxic. Unionized ammonia levels as lowas 0.4 ppm can cause death. Reduced growth andtissue damage can occur at 0.06 ppm.

The ratio of the total ammonia nitrogen (TAN)in the un-ionized form depends on temperature andpH (Table 7). The amount of toxic unionized am-monia increases as temperature and pH increase.Under reasonable feeding rates and good water qual-ity conditions, ammonia is seldom a problem.

Ammonia can become a serious problem,however, if:

Overfeeding is common.A sudden algae or phytoplankton die-off occurs.A high afternoon pH drives the un-ionized am-

monia concentration to a toxic level.

Ammonia levels should be routinely checkedeach week and whenever an algae die-off occurs.High ammonia levels can occur at any time of theyear, but they are most likely during the summerbecause of heavy feeding rates. Managing high am-monia levels is difficult. First, stop or reduce feed-ing rates and maintain good dissolved oxygen levels(ammonia damages the gills). Second, flush thepond if adequate water is available.

Nitrite Toxicity. Nitrite is also very toxic to cat-fish. Under normal conditions, nitrite does not ac-cumulate to toxic levels. But it can reach toxic levelsif bacterial decomposition (nitrification) is disrupted.Most nitrite problems occur during fall and winter,when sudden changes in pond water temperaturesdisrupt bacterial decomposition.

Nitrite passes through the gills of fish and at-taches to hemoglobin of the blood, formingmethemoglobin. Methemoglobin causes the blood to

Table 7. Percentage Of Un-ionized Ammonia In Solution At Different pH And Temperatures.

Temperature °C

pH 16 18 20 22 24 26 28 30 32707.27.47.67.88.08.28.48.68.89.09.29.49.69.8

10.0 74.78 77.4610.2 82.45 84.48

0.30 0.340.47 0.540.74 0.861.171.842.884.496.9310.5615.7622.8731.9742.6854.1465.17

1.352.123.325.167.9412.0317.8225.5735.2546.3257.7768.43

0.400.630.991.562.453.835.949.0913.6820.0828.4738.6950.0061.3171.5379.9286.32

0.46 0.52 0.600.72 0.82 0.951.14 1.30 1.501.79 2.05 2.352.80 3.21 3.684.37 4.99 5.716.76 7.68 8.7510.30 11.65 13.2015.40 17.28 19.4222.38 24.88 27.6431.37 34.42 37.7142.01 45.41 48.9653.45 56.86 60.3364.54 67.63 70.6774.25 76.81 79.2582.05 84.00 85.8287.87 89.27 90.56

0.701.101.732.724.246.5510.0014.9821.8330.6841.2352.6563.7973.6381.5787.5291.75

0.811.272.003.134.887.5211.4116.9624.4533.9044.8456.3067.1276.3983.6889.0592.80

0.951.502.363.695.728.7713.2219.4627.6837.7649.0260.3870.7279.2985.8590.5893.84

change in color from red to chocolate-brown. For thisreason, nitrite toxicity is called “brown blood” dis-ease. If you suspect “brown blood,” check the gillcolor or cut off the tail of a fish and look for chocolate-colored blood.

Normal hemoglobin carries oxygen through thebloodstream, but methemoglobin cannot. Fish in thiscondition are under severe respiratory stress and willshow signs of oxygen depletion. Nitrite toxicity is af-fected mainly by temperature, dissolved oxygen, andchloride ions. A nitrite concentration as low as 0.5ppm can cause stress.

Nitrite concentrations can rise from 0 ppm tolethal levels in 2 to 3 days, so it is very importantto test for nitrite regularly. Producers should checknitrite concentrations three times per week from Au-gust 15 to January 1 and throughout April and May.Checking nitrite one or two times a week is suffi-cient the rest of the year. Producers should also mo-nitor nitrites closely after algae die-offs.

Chloride ions (not chlorine) in the water can blocknitrite from entering across the gills, protecting thefish from “brown blood.” Research has shown thata minimum of 3 parts of chloride should be presentfor each part nitrite in the pond. Generally, a chlo-ride to nitrite ratio of 5:l or 6:l is best.

Salt (sodium chloride) is commonly used to in-crease chloride concentrations in ponds. Calciumchloride, either anhydrous or dihydrous, has also beenused for this purpose, but it is more expensive.

Some producers try to maintain chloride concen-trations at 30 ppm in ponds. Applying 45 pounds ofsalt in 1 acre-foot of water will bring the chloride levelto 10 ppm. So, to achieve 30 ppm, 135 pounds (45x 30) is needed for each acre-foot of water. In a10-acre pond with an average depth of 4 feet (or atotal of 40 acre-feet), a 30-ppm chloride concentrationwould require the addition of 5,400 pounds of salt.

A more precise way to calculate the needed lev-el of chloride is to measure the nitrite concentrationand multiply it by 6.

Whenever nitrite levels rise, check chloride levelsand add salt as needed. Flushing water through thepond can reduce nitrite levels but will also removechloride ions. Watershed ponds lose chloride whenthey overflow. Test regularly and keep good records!

After the “brown blood” problem is corrected,watch the fish closely for bacterial infections. Bac-terial infections often occur a few days after “brownblood” outbreaks.

Other Toxicity Problems. There are otherpotentially harmful chemical compounds thatproducers should consider.

Copper and zinc in small concentrations can beextremely toxic to fish. Galvanized equipment, suchas pipes, containers, screens, and tanks used in hold-ing and transporting fish may give up enough zinc tobe toxic. Copper from algae treatment, pipes, andother equipment can also be toxic to fish in containers.

Catfish are very sensitive to chlorine. Waterfrom city supplies should not be used for filling, haul-ing, or holding tanks.

Some pesticides are also toxic to fish. Fish inponds built on cultivated watersheds are always indanger of pesticide poisoning. Before stocking fishin these ponds, find out which chemicals have beenused and their toxicity to fish.

Establish vegetative barriers between fields andponds. Make sure that chemical applicators preventchemical drift over ponds. Be aware that constantuse of chemicals near ponds may eventually causea serious problem.

In the future, one of the strongest selling pointsfor aquaculture products should be their lack ofchemical contamination. Keep dangerous chemicalsaway from your ponds and assure the consumer ofthe highest quality product.

Table 8. Recommended Water-Quality Require-ments For Catfish Production.

Component

Dissolved oxygenCarbon dioxidepHTotal alkalinityTotal hardnessUn-ionized ammoniaNitriteTemperature change

RecommendedValue Or Range

4 ppm or moreless than 20 ppm6 to 9.520 ppm or more20 ppm or moreless than 0.05 ppmless than 0.5 ppmless than 5°Fas rapid change

Parasites And DiseasesLow oxygen, handling, crowding, transporting,

and poor nutrition all cause stress, making fish moresusceptible to parasites and diseases. If fish feedslowly or stop altogether, appear sick, or die, ana-lyze the situation immediately.

Test the water to see if the condition could becaused by low oxygen, high carbon dioxide, ammo-nia or nitrite toxicity, or pesticide pollution. If theseproblems can be eliminated, watch the fish closely.

Are the fish:l not eating?l lying lazily in shallow water or at the surface

and not swimming off rapidly when disturbed?l nervous or irritable?l flashing or swimming erratically?

Catch some fish that seem sick. Do they have:l worn-away areas on gills, fins, mouth or skin?l open sores?l heavy mucous (slime) covering all or parts of

their bodies?l pale or swollen gills?l protruding eyes?l swollen or sunken bellies?

Figure 16 shows several signs of disease. If yousee any of these signs, get a diagnosis immediately.Early diagnosis is essential for effective treatment.

Figure 16. Diseased catfish fingerling.

The Southeastern Cooperative Fish DiseaseProject diagnoses fish diseases free of charge duringworking hours Monday through Friday.

Send your samples to:Fish Disease Laboratory, Swingle HallAuburn University, Alabama 36849-5419844-9307 or 844-4786.

Or, if you live in the Greensboro area, send them to:Alabama Fish Farming Center529 Centreville StreetGreensboro, Alabama 36744624-4016 or (800) 838-2332

A good diagnosis depends on proper sample col-lection and transportation. Samples must be trans-ported quickly. If possible, bring your fish to thedisease lab in person.

Bus transportation is most reliable when shippingto Auburn. Shipping by overnight carrier may be pos-sible, but check with the carrier. Include a separatewater along with the fish, so that water qual-ity can be checked.

Finally, always call the disease lab and confirmthe shipment.

Results of bacterial diagnosis take 2 or 3 days. Thepond owner will be notified of the results and recom-mended treatments as soon as they are available.

More information on collecting and sending sam-ples to the diagnostic labs can be found in Exten-sion circular ANR-562, “Guidelines For CollectingAnd Shipping Diseased Fish.” This publication isavailable from your county Extension agent or theExtension fisheries specialists.

ChemicalsChemicals should be used in fish culture only

when there is no alternative. Ponds can require chem-ical treatment for:

l controlling disease.l sterilizing ponds.l altering water quality.l eliminating undesirable fish.l controlling undesirable insects and weeds.

Not all agricultural chemicals are approved for usein food fish ponds. Check with your county Exten-sion agent or Extension fisheries specialist for thelatest recommendations.

When chemical treatment is prescribed, how doyou calculate the amount of chemical needed to getthe required concentration? Before treating any bodyof water, you must consider these things.

c

The FishWhat are the tolerable limits of the fish to the

chemical?

The WaterIn the pond to be treated, what water quality fac-

tors will affect the chemical being used?Could hardness or muddiness increase the toxic-

ity of, or render ineffective, the chemicals being used?

The ChemicalWhat percentage of active ingredient is in the

chemical formulation?

The Pond SizeWhat is the exact volume of water to be treated?

Many fish have been killed because pond volumeshave been exaggerated. Overestimating the pond sizewill cause an overdose and probably kill fish. On theother hand, underestimating the size may result inan ineffective treatment.

Know the volume of your tanks and ponds. Keepa record of this volume for future treatments.

To calculate the volume of a square or rectangu-lar body of water, multiply length times width timesaverage depth of water. This will give you cubicmeasurements of volume. Cubic feet (ft3) and acre-feet are the measurements most commonly used.The area and volume of irregularly shaped ponds aremuch more difficult to determine.

The local SCS office can assist you in determin-ing surface area and possibly average depth. Aver-age depth can be estimated by multiplying themaximum depth by 0.4. Remember to use the sameunits of measure for each body of water to be treated.

One very accurate way to measure pond volumeis through the use of chloride tests.

1. Take a water sample from the pond and testit for chloride (ppm). Reserve this sample so it canbe compared to later samples.

2. Broadcast 50 pounds of salt per surface acreof the pond. The total pounds of salt added must beknown, but the pond acreage can be estimated.

3. Allow the salt to dissolve. Usually one day issufficient.

4. Take several water samples from differentareas and depths of the pond. Test these new sam-ples for chloride concentration.

5. Calculate the average chloride concentration.Add the chloride concentrations of all the samplestogether. Divide by the number of samples.

6. Calculate the change in chloride concentration.Subtract the beginning chloride concentration (theconcentration of the very first sample) from the aver-age chloride concentration.

7. Calculate the pond volume using this formula:

Volume (in acre-feet) =(weight of salt applied x 0.6) + 2.71

change in chloride concentration (ppm)

Measure accurately! Since 1 acre-foot of waterweighs 2.7 million pounds, then 2.7 (2.71 in the for-mula above) pounds of any material (or active ingre-dient) dissolved in 1 acre-foot of water gives a solutionof 1 part per million (1 ppm). This method will notwork in hill-type ponds that are stratified.

The volume of water in watershed ponds mayvary considerably from month to month. A producershould know the volume of ponds at different ponddepths, so that chemicals can be applied correctly.Remember, low estimates may result in ineffectivetreatments and high estimates may cause overdosesand fish kills.

Table 9 shows the weights of chemicals that mustbe added to 1 unit volume of water to get a concen-tration of 1 ppm.

Table 9. Chemical Active Ingredients Needed ToProduce 1 ppm Concentrations.Amount Active Parts PerIngredients Unit Of Volume Million2.7 Pounds acre-foot 1 ppm1,235 grams acre-foot 1 ppm1.24 kilograms acre-foot 1 ppm0.0283 grams cubic foot 1 ppm1 milligram liter 1 ppm8.34 Pounds million gallons 1 ppm0.0038 grams gallon 1 ppm

Table 10 contains conversions that are helpful incalculating treatments. More conversions to assist inchemical treatments can be found in Extension cir-cular ANR-414, “Tables For Applying CommonFishpond Chemicals,” available from your countyExtension agent or the Extension fisheries specialists.

Table 10. Conversions For Treatment Calculations.1 acre-foot =1 surface acre of water 1 foot deep

=43,560 cubic feet=2,718,000 pounds of water=326,000 gallons of water

1 cubic foot =7.5 gallons=62.4 pounds of water=28,355 grams of water

1 gallon =8.34 pounds of water=3,800 cubic centimeters=3,800 grams of water

1 quart = 950 cubic centimeters=950 grams of water

p i n t =475 cubic centimeters=475 grams of water

cup =240 grams of water

tablespoon =14.8 grams of water

teaspoon =4.9 grams of water

1 pound =454 grams

1 ounce

1 liter

=I6 ounces

=28.35 grams

=I000 grams of water

Off-flavorOff-flavor in farm-raised catfish is a very impor-

tant problem to producers. Off-flavor is the presenceof objectionable flavors in the fish’s flesh. The off-flavor may be so intense that it makes the fish un-marketable.

During the fall, more than 50 percent of produc-tion ponds may have off-flavor fish. This means thatponds cannot be harvested, and harvest and process-ing schedules are disrupted. Producers are left feed-ing and maintaining these fish, which increasesproduction costs, disrupts cash flow, and extendsrisks.

Off-flavor is a complicated problem and requiresthat producers understand the probable causes, pos-sible cures, and, most important, how to check thefish before they are marketed.

Off-flavor is caused by chemical compoundswhich enter the fish from the water. Research has

shown that some of these compounds are producedby certain pond bacteria and algae.

The bacteria belong to a group of filamentousbacteria called the actinomycetes. These bacteria arefound in the water column, but they are most abun-dant in the bottom mud. Actinomycetes thrive inponds during warm weather, using nutrients fromfish wastes and uneaten feed.

,

Algae commonly associated with off-flavors be-long to the blue-green group. Blue-green algae,though always present in ponds, are most abundantin the summer and fall. Blue-green algae also thrivein nutrient-rich ponds and can dominate other typesof algae. Blue-green algae often float and form paint-like scums or a “soupy” layer near the surface.

Off-flavors can be described in many ways. Pos-sible descriptions include: earthy, musty, rancid, woo-dy, nutty, stale, moldy, metallic, painty, weedy, putrid,sewage, petroleum, and lagoon-like. Obviously, manycompounds and causes are involved. The causes ofsome off-flavors are still to be identified.

Two specific compounds have definitely beenidentified as producers of off-flavors: geosmin and2-methylisobomeal (MIB). These compounds areproduced by both blue-green algae and actinomy-cetes. Geosmin causes a musty or woody off-flavor,and MIB causes a musty or weedy off-flavor. Bothproduce off-flavor in minute concentrations of 2 to3 parts per billion (ppb) in pond water.

Off-flavor compounds are eliminated from theflesh of the fish in time, if the compounds are nolonger in the pond. Depending on temperature andother weather conditions, it can take from a few daysto more than a month for the sources of off-flavorand the off-flavor itself to dissipate.

A producer can do very little about off-flavor ex-cept wait for it to go away. It is nearly impossibleto control the bacteria or algae in the pond. The useof herbicides to control the algae is not effective.Research in Arkansas has found that stocking cat-fish ponds with tilapia reduced the occurrence of off-flavor. Problems of obtaining tilapia fingerlings, con-trolling reproduction, and finding a market for themare still to be solved, however.

Placing fish in clean water is another option. Thismethod works well, but it is costly in terms of facili-

Processors check fish for off-flavor before

ties, labor, energy, time, and weight loss of the fish

scheduling harvests. Producers should check fish foroff-flavor also. Start checking the fish at least 2

being held.

weeks before the planned harvest, again 3 days be-fore harvest, and finally the day of harvest. Fish cango off-flavor within a few hours and even during har-vest operations. If off-flavor is found, continue test-ing weekly. The future of the catfish industrydepends on a quality product, so every producermust make sure that the fish are not off-flavor.

Use the following procedure to test catfish for off-flavor:

1. Select one fish from each pond.2. Head and gut, but do not skin the fish. This

step can be skipped if you do not plan to eat the restof the fish later.

3. Cut off the tail section (the last third) with skinintact. Use this part for the test.

4. Cook the tail section until the flesh is flaky,using one of the following methods. Do not seasonthe fish with any spices, not even salt.

l Wrap the fish in foil and bake at 425 °F forabout 20 minutes.

l Place the fish in a small paper or plastic bagor a covered dish and microwave at high powerfor 1 1/2 minutes per ounce.

5. After cooking, smell the fish first. Do you no-tice any foul odors?

6. Next, taste the fish. Do you notice any foul orbad flavors?

Learn to check your fish. Know when an off-flavor problem exists. And remember, a first-timecatfish consumer who eats an off-flavor fish may bea one-time customer.

HarvestA market for fish must be arranged before har-

vesting. Most buyers prefer fish that weigh between3/4 and 2 pounds.

MethodsTwo harvesting methods are generally used:

complete harvest, when all the fish are taken outof the pond, and partial harvest, when only a por-tion of the fish are taken out of the pond at one time.

,,,, ,,,,, , , , I I

_ .

A complete harvest is usually done by seining anddraining the pond. In levee-type ponds, the pond isseined to remove the fish. In hill-type ponds, the pondis seined to remove the fish as soon as the water islowered to about 5 to 8 feet deep at the drain. Theremaining fish, in both cases, are captured by seinesand dip nets from the small pool of water remainingnear the drain after the pond is drained.

Draining is the best way to harvest all the fish atone time. However, water is lost and refilling can becostly. In watershed ponds, refilling depends mainlyon rainfall, which can keep ponds out of productionduring dry periods.

One solution to this problem is to drain or pumpwater from the pond being harvested into other near-by ponds for temporary storage. Then, refill the har-vested pond from the storage pond. Harvesting fora series of ponds should start at the lowest pond andend at the uppermost pond, thus conserving most ofthe water.

Concentrating the fish in a small area when wateris drawn down may cause an oxygen depletion whichcan kill them. Careful supervision is required duringthis procedure. Aerated well water or tractor-poweredaerators are needed during harvest in the event ofoxygen problems. Be sure to have adequate facilitiesto hold the remaining fish, if all your fish cannot behauled to market in a reasonably short time.

Partial harvest can be done by angling, trot line,trapping, or seining. Angling, trot lines, and box trapsare usually too inefficient for commercial harvest.Seining ponds without draining is difficult in manyAlabama ponds. Most hill ponds are too deep and un-even to seine. Partial harvesting by using a seine fortrapping the fish can be very effective, however. Thismethod is especially useful when fish buyers wantsmall quantities of fish for local sales.

Generally, a seine 150 to 200 feet long and 6 to8 feet deep should be used for trapping. Set the seinein a location that has a smooth bottom and is about3 to 4 feet deep at a distance of 50 feet from shore.Stretch the seine parallel to the shore at a distanceof approximately 50 feet. Coil 50 feet of the seine ateach end and connect a rope from each coiled endto the shore. The seine can also be set in the centerof a finger or bay of the pond, if the seine is 1 1/2 timesthe width of the bay

Set the trap and begin feeding between the seineand the shore for several days before attempting aharvest. Sometimes feed must be spread outside thecatch area to lead fish into the trapping area. The fishwill be ready to trap after several days, when theyare well accustomed to feeding within the area. Placea small amount of feed within the trapping area andpull the seine ends to shore when the fish are feed-ing. Then carefully draw the entire seine to shore andharvest the fish. Figure 17 shows the placement ofa seine.

Figure 17. Placement of seine and haul ropes.

The trap-seine method of partial harvest usuallycannot be used more often than once every 7 to 10days, because fish become wary of the trap. However,harvesting can be alternated among ponds or at differ-ent stations within larger ponds. Remember to feedfish at the time of day you plan to trap. More infor-mation on trap seining can be found in Extension cir-cular ANR-257, “Corral Seine For Trapping Catfish,”available from your county Extension agent or the Ex-tension fisheries specialists.

EquipmentThe type and size of harvest equipment a

producer needs depends on the size of the operationand the market served. Some producers harvest theirown fish. However, some fish buyers and custom har-vesters harvest the fish, reducing the producer’s needfor equipment.

Seines. For every 2 feet of pond width to be seined,3 feet of seine length is required. The same ratio ap-

plies to pond depth. Floats can be made of styrofoamor plastic attached on 18-inch centers.

Most catfish seines have a mud line on the bot-tom of the net. A mud line is made of many strandsof rope or a roll of menhaden netting bound together(Figure 18). As the seine is drawn across the pondbottom, the mud line stays on top of the mud,eliminating the digging effect of lead-weighted lines.

Figure 18. Catfish seine fitted with mud line.

Seines should be made of polyethylene or nylon.Catfish spines will not catch in polyethylene materi-al. Nylon netting requires a net treatment to preventspines from entangling.

The mesh size to be used varies according to theminimum size of the fish to be captured. Buying theproper mesh seine for your operation allows you tocapture only fish that are large enough for your mar-ket. Table 11 gives the size of fish that can be caughtby various sizes of mesh. The size of the fish caughtvaries somewhat with the mesh width and the con-dition and activity of the fish. Fish do not grade aswell when water temperatures are cold. All sizes aregiven as bar mesh, which is the smallest distancebetween knots.

Table 11. Mesh Sizes And Sizes Of Fish Caught.

Mesh Size Fish Size

1 inches 5 ounces and larger1 1/4 inches 7 ounces and larger1 3/8 inches 8 ounces and larger1 1/2 inches 12 ounces and larger1 5/8 inches 1 pound and larger1 3/4 inches 1 1/2 pounds and larger1 7/8 inches 1 3/4 pounds and larger2 inches 2 pounds and larger

Live-cars. Holding live fish is sometimes necessaryif the market cannot take all the catch in one day,or if there is a delay between capture and haulingfish to market. Often, catfish producers may wantto sell fish directly to consumers. In these cases, cat-fish can be held in live-cars. Live-cars are net en-closures that can be placed in a pond to temporarilyhold the fish (Figure 19). They are made of the samematerials as seines.

Figure 19. A live-car.

Use caution when holding fish in live-cars. Dis-eases, oxygen stress, weight loss, and poaching arecommon problems. It may be necessary to aeratenear the live-car at night, particularly in warmweather. Limit the time the fish are held to only afew days to reduce weight loss and prevent disease.Disease can occur in holding devices during any sea-son but is much more prevalent when water tem-peratures are highest. Poachers can easily steal fishfrom unguarded holding facilities.

Other equipment. For harvesting fish, producersmay also need:

A seine reel for hauling in and storing the seine.Seine stakes.Tractors.Sturdy dip nets.Baskets.Boots or chest waders.Scales.A boom.A boat and motor.A gasoline-powered pump for filling tanks.Fish hauling tanks (Figure 20).

Fish pumps for loading catfish are also gainingpopularity.

Figure 20. A fish hauling tank mounted in thebed of a truck.

When To HarvestCoordinate your harvest date to meet the needs

of your markets, whether the fish go to processorsor your own private outlet. Make sure that the fishare of the size demanded by your buyer. There aremarkets, such as live-haulers and fish-out operations,that desire larger fish.

Most catfish are stocked as fingerlings in winteror early spring and harvested in the fall or winter.This schedule often results in a glut of fish readyfor market in the fall. To avoid this situation,producers can stock fingerlings of varying sizes atdifferent times of the year. This strategy may notresult in optimum growth, but the higher pricesgenerally paid for market-size fish during the springand summer may make up for any inefficiencies.

Transporting Live CatfishTransporting live fish requires maximum care to

avoid fish losses. In transport, fish are crowded intoa relatively small amount of water. Agitators, blow-ers, compressed oxygen, compressed air, or liquidoxygen can be used individually or in combinationto keep the fish alive. Transport containers are usual-ly made of wood, fiberglass, or aluminum. Manytypes are commercially available.

Generally, the dissolved oxygen content in thewater is the factor that determines whether the fishlive or die. Fish should not be fed for at least 24hours before transport so that excessive fish wastesdo not accumulate during transport. Fish wastes andregurgitated feed consume large quantities of oxy-gen and can produce ammonia and carbon dioxideproblems.

Transporting fish in cool weather or in cool wellwater increases fish survival. Cool water holds moreoxygen than warm water, and fish consume less oxy-gen at lower temperatures. Also, large fish consumeless oxygen by weight than small fish. It is a goodpractice to have an oxygen probe in the hauling tankand the meter in the cab of the truck to monitor oxy-gen concentrations during transport.

Fish health and survival depend on your abilityto limit stress. Stress from netting, loading, hauling,and stocking weakens the fish and makes them moresusceptible to disease and water-quality problems.The more you limit stress factors, the healthier thefish will be.

Table 12 (page 20) shows some guidelines forhauling live catfish. The numbers are in pounds offish per gallon of water in tanks using agitators orblowers for aeration. Assume that the water temper-ature is 65

_

Table 12. Load Limits For Hauling Catfish, InPounds Of Fish Per Gallon Of Water.”

Duration Of Transport

Size Of Fish 1 Hr. 6 Hr. 12 Hr.24 Hr.

pounds of fish per gallonof water

Z-inch fingerlings 2 1 1/2 1 18-inch fingerlings 3 3 2 1 1/214-inch adult fish 4 4 3 2*Adapted from Transport of Live Fish by S. K. Johnson, Texas A&MUniversity.

As water temperature rises, decrease the load by25 percent for each increase of 10 °F The same cal-culation can be used for increasing the load as tem-perature decreases. Loads can be increased by about25 percent when pure oxygen is used for aeration.Ice can be used to cool the water in hauling tanks.Be sure to temper the fish before stocking or load-ing them into water of a different temperature (referto the Water Quality section for the temperingprocedure).

Marketing CatfishBefore the first ponds are built or before fish are

stocked in existing ponds, producers should knowwhere they can sell their fish. The market optionsavailable to catfish producers include:

l Large processors.l Small processors.l Fish-out, on-farm sales.l Local retail sales.l Live-haulers.

A market should be selected based on the potentialprofits according to the scale of the operation. Eachoption should be carefully analyzed.

Large processors generally harvest fish forproducers within a short radius of the processingplant (50 to 75 miles). Some accept fish deliveredlive by the producer. Fish producers within range oflarge processing plants should arrange harvest ordelivery dates before fingerlings are stocked.

Many producers want to sell their fish in the fall,creating an oversupply of fish for the processors. Cat-fish harvested in the spring or summer usually com-

mand a higher price, because processor demand ishigher and supplies are lower. Some producers areable to market their fish more profitably during timesof short supplies by manipulating the fingerling sizeand the stocking date and by partial harvesting.

There are small-scale processors in some areaswho process small quantities of catfish for sale to lo-cal businesses and individuals. These processorsoften produce much of their own fish but, at times,buy from local producers. Your county Extensionagent has information concerning processors in yourarea. Information on building your own small-scaleprocessing plant can be found in Experiment Sta-tion Bulletin 255, “Design Of Small-Scale CatfishProcessing Plants In Alabama,” available from theAlabama Agricultural Experiment Station at AuburnUniversity.

Fish-out, or fee fishing, is another market optionfor many catfish producers. A fish-out business de-pends on the numbers of fishermen in the area andtheir ability to catch fish. Fishing ponds located nearcities are usually more in demand than in remoteareas.

Small, densely stocked ponds are best for fish-out purposes. Catfish should be replenished whenstocks become low, so that the fish will keep biting.Many successful fee-fishing operations buy fish fromother producers or produce them in their own pondsto stock fish-out ponds. This results in better fish-ing success, more customers, and more sales.

Owners of fish-out operations should be awareof safety provisions necessary when opening pondsto the public. Insurance protection against liabilityclaims is a must!

Wholesale and retail sales of live catfish are otherways for producers to sell their product. Fish can becaptured to order or captured and held live for latersale. Local newspaper ads, road signs, and word-of-mouth can rapidly establish a good market. Remem-ber that customer demand can be maintained byproviding a consistent supply of high-quality catfishthroughout the year.

Live-haulers, people who buy and haul live cat-fish from producers to retail outlets, are importantbuyers of farm-raised catfish. Usually these haulers

want producers to harvest and load the fish into theirtank trucks. Live-haulers often transport fish to fish-out ponds or other live markets near large cities suchas Chicago or Atlanta. Live-haulers generally buy themajority of their fish from March through October.

A producer catering to live-haulers exclusivelyshould have all the necessary equipment for seiningand loading, plus all-weather roads around theponds.

Bird PredationBird predation has been an increasingly serious

problem for catfish producers since the mid-1980s.Most birds that cause problems are migratory andare therefore protected under the federal MigratoryBird Treaty Act (MBTA). The birds’ migratory na-ture complicates the problem, because predationvaries greatly depending on migration patterns, timeof the year, migratory concentrations, and the loca-tion of catfish ponds. Proximity to nesting or rook-ery sites can also compound the problem.

Besides eating the fish, these birds can damageproperty. They are known to transmit fish diseases.Predatory birds consume the individual fish that areeasiest to catch. Fish that are easily caught are oftenthose that are diseased. So, the birds pick up dis-eases and transmit them to other ponds through theirexcrement and through simple body contact.

Catfish in Alabama are preyed upon by cor-morants, egrets, and herons throughout the year andby kingfishers and anhingas (water turkeys) duringthe warmer months. Ospreys and pelicans can some-times cause problems, too. The occasional visit bysolitary kingfishers and ospreys causes little econom-ic damage. Frequent visits by flocks of anhingas, he-rons, egrets, pelicans, and cormorants can bedevastating, however. The problem is generally mostpronounced in fingerling ponds.

The MBTA is often confused with the endan-gered species laws. Under the MBTA, migratorybirds may not be killed or trapped without permits.But the species mentioned above can be harassedor frightened away from ponds, and habitat altera-tion and physical barriers are possible methods ofcontrol.

Physical barriers can include hanging netting orwires over ponds and erecting fences around the

edge of ponds. These measures are expensive andmay cause physical problems to the producer duringharvest.

The most common control measures are harass-ment techniques to frighten birds away from ponds.Birds can be frightened away by:

Gunfire.Fireworks.Gas-powered noise cannons.Electronic noisemakers.Flashing lights.Reflecting material.Repellents.Bird distress calls.Water fountains or cannons.Scarecrows.Electronic shocking devices.

These measures have had mixed success. Mostmethods appear to be effective at first, but they be-come ineffective as the birds get used to them. Forthis reason, it is best to use a combination of tech-niques and to frequently move the devices randomlyaround the ponds.

Producers may contact the US. Fish and WildlifeService and the USDA’s Animal and Plant Health In-spection Service (APHIS) for assistance. These agen-cies will recommend control measures. Permits canbe issued to kill birds, if producers keep good recordsof control measures and estimated losses of fish.These permits are only issued after other methodshave proved (by working through agencies and keep-ing good records) ineffective as certified by theAPHIS Animal Damage Control Office. Comply withthe law, try creative harassment techniques, reportlosses to state and federal agencies, and keep goodrecords.

Genetics And BreedingImproving catfish through genetic research is a

relatively new activity. Much of the improvement inthe last 40 years in all phases of agricultural produc-tion, both plant and animal, has resulted from geneticselection and hybridization. Faster growth, higheryield, better feed conversion, and increased resistanceto disease can all be improved through geneticmanipulation.

Several universities in the Southeast are involvedin catfish genetic research. Scientists are doing workin selection, strain identification and evaluation,cross-breeding, hybridization, polyploidy, sex revers-ing, and gene splicing. The results of this researchare encouraging, and this type of research is ex-panding.

In general, domesticated strains of catfish haveshown better growth rates than wild strains. Themany domesticated strains vary in growth rates, bodyconformation (influences dress-out percentage), andresistance to disease. Crossbreeding has also shownsome improvements in growth rates, spawning suc-cess, and disease resistance (attributable to hybridvigor). Of course, not all strains or crossbreeds per-form equally at different geographical locations.

Crossing female channel catfish with male bluecatfish has produced improved growth, feed conver-sion, resistance to certain diseases, catchability byseining and angling, and higher dress-out as com-pared to pure channel catfish. However, productionof the channel female X blue male hybrid can bedifficult. The two species rarely spawn naturallywhen mated together, and they spawn inconsistent-ly even when expensive hormone injections are used.Research is continuing so that this significantly im-proved fish will be available to producers in thefuture.

From a practical standpoint, producers shouldwork with domesticated strains. If you buy your fin-gerlings, buy from a producer who is practicing massselection or who is working with improved strains.If you produce your own fingerlings, know whatstrain you have, try mass selection of your fastestgrowing fish, try to obtain improved strains for cross-breeding, and, most importantly, do not inbreed.

For help in identifying strains and understand-ing genetic improvement techniques request: Circu-lar 273, “Ancestry and Breeding of Catfish in theUnited States,” and Southern Cooperative SeriesBulletin 325, “Genetics and Breeding of Catfish.”These publications are available from the AlabamaAgricultural Experiment Station at AuburnUniversity.

More information on producing catfish finger-lings can be found in Extension circular ANR-327,

“Producing Channel Catfish Fingerlings,” availablefrom your county Extension agent or the Extensionfisheries specialists at Auburn University.

Permits And RegulationsNo fish farming permit is required in Alabama.

Processing facilities, however, must be certified andinspected by the Alabama Department of PublicHealth.

Permits to construct ponds are needed if theponds are to be located in wetlands. Before construct-ing ponds, check with the USDA Soil ConservationService for the latest information on permits requiredfor building ponds. When constructing in a wetland,failure to have a permit from the Corps of Engineerscould result in civil and criminal penalties.

Discharge from ponds must meet federal En-vironmental Protection Agency (EPA) standards asadministered by the Alabama Department of En-vironmental Management (ADEM). Under presentregulations, most producers do not need permits.Permits are necessary if a catfish farm producesmore than 100,000 pounds each year and dischargeswater 30 or more days each year. Discharge does notinclude overflow from ponds during rains.

Alabama law (83-152) makes theft of farm-raisedfish the same as livestock rustling. A person con-victed of stealing fish is subject to a fine of not lessthan $500, not more than $1,000, and seizure of theproperty used in committing the theft. This includesthe fishing equipment and the vehicles. The courtcan also imprison the convicted person for up to 1year for the first offense. ’

Check on the laws of other states before trans-porting fish across state lines. Because laws andregulations can change frequently, check with theappropriate agencies if you have any questions.

ReviewThis publication was designed to inform the

general public about the catfish industry and to helpprospective and existing catfish producers make ra-tional investment and operational decisions for com-mercial scale farms. It highlights some of thedifficulties, complexities, risks, and opportunities ofcatfish farming. Catfish farming is one of the mostintensive forms of large-scale agriculture practicedtoday It requires considerable capital investment, andit is a high-risk venture not suited to everyone.

Catfish farming is in its infancy. Problems involv-ing genetic improvement, off-flavor, disease preven-tion, predator control, drug registration, water useand discharge, and market development continue tobe addressed by researchers, Extension workers,government agencies, fish farmers, and other in-terested parties. No one has all the answers requiredfor risk-free operation. The future is bright butshould be approached with caution.

For more information on fish farm-ing or pond management and for copiesof the publications mentioned here, con-tact your county Extension office or anExtension fisheries specialist with theAlabama Cooperative Extension System.

ALABAMA For more information, call your county Extension office. Look in your telephone di-rectory under your county’s name to find the number.

Issued in furtherance of Cooperative Extension work in agriculture and home economics, Acts of May 8 and June

SYSTEMANR- 195

30, 1914, and other related acts, in cooperation with the U.S. Department of Agriculture. The AlabamaCooperative Extension System (Alabama A&M University and Auburn University) offers educational programs,materials, and equal opportunity employment to all people without regard to race, color, national origin, religion,sex, age, veteran status, or disability. UPS 10M55, Rep. 2:97, ANR-195

.....- ~ COOPERA~~ ExtenSion