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FISH SEED REARING AT

EXPERIMENTAL SITE IN

COLD WATER CONDITIONS

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Fish Seed Rearing at Experimental Site in Cold Water Conditions .......�

39

3.1 INTRODUCTION

The scarcity of quality fish seed is identified as major constraint in

popularization of fish farming to utilize the rich potential inland water resource

of the country. Till the early sixties, rivers were the only major source of fish

seed supply contributing 92% of total seed supply (NCRET, 1990). The Ganga

river system is the largest river system for obtaining fish seed and is the home

to Indian major carps. Fertilized eggs, spawn, fry and fingerlings constitute

riverine seed. Spawn/fry collection is undertaken in few States. Among

coldwater fish seed resources, trout (exotic) and mahseer are found in the

Himalayan region and the Peninsular Indian Rivers that originate in the

Western Ghats.

The collected seed from riverine sources comprises a mixed lot of fish

seed and may include uneconomical and predatory fish seed. Further, as such

fish seed remains available at some specific locations on rivers only. There is

great difficulty occur in transporting the fish seed to market. Rivers are natural

and traditional sources of fish seed for aquaculture.

In this regard to increase seed production of carp species several

technologies have been developed to breed indigenous and exotic carps and

raise their seed in pond, cages and pens. Limitations of nursery /rearing ponds,

problems in pond preparation and management techniques were recognized as

some of the major contributory factors for reduced seed rearing activities, poor

survival and growth of fish seed. At National level, the mortality rate reported

in rearing spawn up to fry stage is very high (85%) in carp nursery and about

64% from fry to fingerlings in rearing ponds (Alikunhi et al., 1984). Several

workers speculated that through developing improved spawn rearing

technology targeting survival of at least 60%, it is possible to meet the country

demand for fish seed without increasing nursery /rearing area. Under the

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national aquaculture strategy, intensive spawn rearing @ 100 million/ha aiming

at survival of about 70% can be adopted with rearing pond condition.

Among the different states, West Bengal is ranked first in inland fish

production as well as fish seed production (8400 million fry/anum). A notable

advance in fish culture was the construction of bundhs for carp breeding in

Bengal. The bundhs are more dependable source of fish seed of selected

cultivable species. Since the success achieved in including Indian Major Carp

to breed in captivity by Chaudhary and Alikunhi (1957). Considerable progress

has been made to produce hatchlings through hypophysation on commercial

level in our country. Advances made in the designing, construction and

management of hatcheries have undoubtedly contributed a lot, to promote

Indian major and exotic carp seed production in bulk. Improved methods of

fish breeding through tasted technologies can ensure increased seed production.

India produces about 17000 million fry per year.

Presently, hatcheries account for 95 percent of seed source. A steady

increase in fish seed production from the 1980s can be attributed to the use of

Chinese carp hatchery technology and the application of ready-to-use spawning

agents. There are more than 420 carp hatcheries, producing about 34,292

million spawns (17,000 million fry). In India the Chinese carp hatchery is most

widely used, followed by the jar hatchery. Ovaprim is the most popular

spawning agent and other one is ovatide. Fish pituitary extract is also used in

some states. Carp seed are also produced in bundhs by simulating riverine

conditions during monsoon. The sources of brooders are mainly seed of farms

or grow-out of farms. Brood fish is normally fed with the traditional feed of

rice bran and oilcake as well as special feed consisting of locally available

ingredients, with fishmeal being an essential component. Carp seed rearing is

carried out in two stages, nursery and rearing, where the survival of fry is only

30% and 50% respectively. Basic ingredients of larval feed are mostly rice bran

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and mustard oilcake. Natural food is promoted through manuring. Availability

of quality fish seed at the right time is most important for sustainable

aquaculture. The causes of poor quality fish seed are: (1) Poor pond

management. (2) Presence of pests (3) Inbreeding (4) Poor management of

brooders and fish seed (5) Transportation stress (6) Mixed breeding (7) Fish

diseases and parasites. Until the 1980s, the fish seed syndicate in Kolkata was

the only source of carp seed, thereafter several states started producing fish

seed and some states are now self-dependent in seed production. There is no

organized fish seed trade in India, however; the best seed trade exists in

Kolkata. Carp seed production in hatcheries and bundhs are found to be

profitable, there is no any definite seed certification exists in the country.

Although the Indian Fisheries Act (1897) exists, it is not possible to enforce

/implement policy matters. The traditional method of transportation for fish

seed is the open system under which the earthen /aluminum /galvanized iron or

tin containers are used for seed transportation. The closed method of

transportation of fish seed in plastic bags with oxygen and water is more

widespread. Brooders are transported in open FRP tanks /plastic pools and

tanks /tarpaulins mounted in trucks.

For the successful carp farming practice in mid hills region, it is

necessary to refine the seed rearing technology in the hilly conditions. As the

pond conditions and water quality remains quite different in hills from the plain

areas, the growth and survival of fish seed also remain affected with these

conditions and there is a need to develop the appropriate seed rearing technique

in mid hills. So, the present study was carried out to develop a feasible

technology of the seed rearing in the hilly conditions for better recovery and for

production of quality seed. As per the feedback from the practicing fish farmers

of the hills, there was a large mortality of the seed, procured from the plain area

at the time of stocking in ponds of mid hills due to the water temperature

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difference and the difference in other water qualities. Fish seed produced and

reared in hilly conditions remain more suitable with less mortality and faster

growth. Therefore, the present study was conducted in six rectangular cemented

and poly tanks namely RT-1, RT-2, RT-3, RT-4, RT-5 and RT-6 at Research

station, Lohaghat. The experiment was conducted twice in proceeding years for

6 months duration for the Grass carp and silver carp and for two months for

common carp. The experiment was carried out in cemented tanks with two

treatments of different stocking density in three replications during the year

2007-08. The same experiment was repeated in poly tanks during the year

2008-09.The rearing of the common carp was done separately in different

months due to the unavailability of the spawn of this species in the same

period. The main purpose of this trial was to refine the rearing technology with

appropriate density, feeding practice and suitable pond type. The growth,

production and survival were the observing parameters during this study. The

findings of this study would be helpful for the availability of quality fish seed

for sustainable aquaculture of exotic carps in mid hills region.

3.2 NURSERY/REARING POND MANAGEMENT PRACTICES

For the better recovery of the seed from the nursery ponds depends on

proper pond preparation, pond type, water qualities, and optimum stocking

density, application of organic manure and fertilizers for natural food

production, application of lime for optimum water pH and sanitation of pond,

health monitoring and food and feeding. Pre-stocking management aims to

proper preparation of ponds to remove the causes of poor survival,

unsatisfactory growth, etc., and also to ensure the ready availability of natural

food in sufficient quantity and quality for the spawn/fry. The success of rearing

and survival in the ponds depended on the pond preparation that adopted 12

days before stocking (Rebelahatra, 1982). The objectives of pond preparation

remain to provide sufficient natural food, and prevent from attack by predators

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and parasite that cause heavy mortality. Rebelahatra (1982) conducted the

experiment for common carp seed rearing and concluded that the complete

protection from predators such as tadpoles, frogs, gambusia, beetles and

backswimmers the survival rate of larvae could be maximize.

3.2.1 Application of manure

Application of the organic manure and fertilizer, liming and

supplementary feeding are the main intercultural activity for the pre stocking

management of the spawn/fry rearing nursery ponds. Alikunhi (1957) stated

that organic manure, mainly the cow dung is traditionally used in nursery ponds

is considered to be one of the best organic manure for the use in nursery ponds

in India. Jhingran (1982) opined that the main objective of manuring of nursery

pond is to augment the production of zooplankton, which are the natural food

for carp spawn. Sharma (1974) studied the effect of cow dung, groundnut oil

cake and poultry manure on plankton production and growth of carp spawn.

Plankton density was recorded highest in ponds receiving 1:10 mixture of

groundnut oil cake and row cow dung. Survival and growth of spawn was also

found to be highest in the cake-dung ponds, and is considered to be related to

plankton density.

It is found that the groundnut oil cake and cow dung mixture could be

advantageously used to fertilize the carp nurseries. Anon (1969) has evolved

the day-to-day schedule of fertilizing nurseries in order to get an average

survival of 45% from spawn to fry stage, the stocking density being 6 million

spawn/ha. Shankar and Varghese (1981) studied the effect of a combination of

cattle dung and superphosphate on the growth and survival of carps. The results

showed that addition of superphosphate to cattle dung enhance carp growth and

production. Chattopadhyay and Mandal (1982) investigated the changes in

chemical and biological properties of soil and water of a brackish water fish

pond manured with composted cow dong and raw cow dung. Rapid

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disappearance of added nutrients from available forms suggested short

fertilization period in such ponds. Application of composted cow dung with

urea and single superphosphate effectively increase the production of plankton

and especially bottom soil fauna. Adverse effects of manuring with untreated

cow dung on the growth of bottom fauna indicated that using composted cow

dung might be more beneficial for such ponds. Nayak and Mankal (1990)

studied the effect of cattle manure and supplementary feeding on water quality,

growth and production of common carp under paddy-cum fish culture system.

Cattle manure was found to improve the water quality and the growth

rate of common carp (Cyprinus carpio) in paddy-cum fish culture ponds.

Estimation of the feed conversion ratio and water quality indicated that feeding

beyond 1.5% of the body weight along with the organic manure (3tones/ha/

month) is wasteful and accumulation of the feed in pond caused deterioration in

water quality. Verma and Singh (1996) conducted an experiment on rearing of

carp spawn in nursery ponds enriched with pig manure. They reported better

survival of 33% and growth of 68-690 mg. (20-33 mm. length), 23 days after

stocking in experimental pond enriched with pig manure as compared to 18%

survival and 38-398 mg. gain in weight (17-25 mm. length) in control pond

manured with cattle dung.

3.2.2 Application of lime

Nagarathinam et al. (1998) opined that liming is one of the chemical

treatments normally during pond preparation, as it can enhance soil

condition and water quality. The production efficiency of the pond can be

increased by liming. Hickling (1962) conducted an experiment to determine

the effects of lime stone on ponds at Malacca Research Station. The result,

as obtained at Malacca, showed that there was increase in pH with

increasing dose of lime stone (line). Brown and Gratzek (1980) reported that

liming results in clearing of humic substance which results in deeper light

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penetration and greater photosynthesis, resulting in increased zooplankton

and Phytoplankton production.

3.3 FISH SEED STOCKING MANAGEMENT PRACTICES

Survival of carp’s seed particularly during initial stages of life cycle is

inversely related to the number of fish seed in the pond (Das and Krishnamurty,

1960). Stocking density must be according to the condition of the pond and the

amount of fish food organism available. The rate of stocking density in a well

prepared nursery pond with adequate fish food organism can be as high as 10

million /ha /crop (Sinha and Ramachandran, 1985). Mondal et al. (2000)

evaluated the influence of varying stocking density on growth and survival of

Catla catla fry in nursery cistern. Catla spawn was stocked @ 2.5, 3.0, 3.5, and

4.0 million/ha in triplicate cistern and named as S1, S2, S3 and S4, respectively.

They were fed with diet containing 38.5% protein (soy bean flour and fish meal

based). The best growth and survival of catla fry were recorded in S1 followed

by S2, S3 and S4. However, S4 was found to be cost effective with higher net

return. Alikunhi (1956) stated that depending upon the density of plankton; the

stocking rate varies from 12 lakhs/ha to 20 lakhs/ha. However, much higher

stocking density was mentioned by Hora and Pillay (1962). Sen (1974) reported

66.6% survival against a stocking density of 10 million /ha, whereas, Tripathi

et al. (1979) stocked rohu spawn at an average rate of 10.21 million /ha and

obtained an average survival of 80.73%. Anon (1984) recorded moderate

survival rates which also varied with the species. Rohu spawn reared @ 2.25 to

6.25 million/ha. recorded a survival range of 41- 65%, Catla spawn reared @

2.5 to 4.0 million/ha. recorded the survival of 46.6-62.2%, mrigal spawn reared

@ 2.25 to 3.0 million /ha. recorded the 51-55% survival, silver carp spawn

reared @ 1.25 to 3.5 million/ha recorded 30-40% survival when the fry were

provided with groundnut oil cake and rich polish (1 : 1) as supplementary feed.

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Saha (1991) conducted an experiment on rearing of Labeo rohita spawn at high

density of 1.0 carore /ha to 1.125 carore/ha. in nursery ponds under normal

condition. He reported an average survival of 64.72%, 69.72% and 93.75% and

65 mg. 55 mg. and 32 mg. gain in weight at stocking densities of 1.125

carore/ha. and 1.0 carore/ha. after 13, 13 and 14 days of rearing period,

respectively in three traditionally treated open nursery ponds. The success

indicated the possibility of adopting the technique on mass scale to cope up

with increased demand in future. Horvath et al. (1992) proposed a stocking

density ranging from 1 to 4 million/ha .for carp seed rearing in nursery pond

under semi intensive management. Basavaraja and Antony (1997) reported an

average survival of 98% and growth of 97 mg. (17.20 mm. length) of common

carp from spawn to fry in the nursery phase where the stocking density was 1.2

million spawn/ha. (3000 no’s /25 m2) and the larvae received only conventional

diet in addition to initial manuring. They stated that that good survival obtained

in this study is mostly attributed low stocking densities, complete eradication of

aquatic insects and presence of aquatic plankton and artificial feed. Sinha and

Ramachandran (1985) stated that stocking density must be according to the

condition of the pond and the amount of fish food organism available. The rate

of stocking density in a well prepared nursery pond with adequate fish food

organism can be as high as 10 million /ha/crop. Jena et al. (1998) conducted an

experiment to assess the growth and survival of Indian major carp fry at

different stocking densities i.e. three stocking densities, 2.5, 5.0 and 7.5

million/ha. for catla and four densities, 2.5, 5.0, 7.5 and 10.0 million/ha. for

rohu and mrigal. Growth of carp fry in terms of length/weight was maximum in

ponds with the lowest stocking density of 2.5 million/ha. Growth of catla was

found to be higher than rohu and mrigal at similar densities. The maximum

survival rates obtained were 61.6%, 67.8% and 69.9% in catla, rohu and mrigal,

respectively at 2.5 million/ha stocking density. They stated that, in general

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Fig. 5 : Fingerlings of carps

Fig. 6 : Fish seed in the poly bag

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growth and survival decreased with increase in stocking density. Dinesh and

Nair (2000) carried out investigation on high stocking density rearing of Labeo

rohita spawn in indoor tanks with eight different diets consisting of live feeds,

formulated feeds, conventional feeds and different combination of the above at

stocking density of 10,000/m3, for duration of 21 days. The diets of Artemia

nauplii and Moina have given higher mean specific growth rate (16.45 and

15.3, respectively) and normalized biomass index (352.12 and 267.76,

respectively) without any statistical significant difference, while Moina plus

formulated feed and artemia plus formulated feed have given higher mean

survival rate of 88.6% and 88.3%, respectively. Sharma et al. (1998) conducted

an experiment to evaluate the growth and survival of grass carp at different

stocking density using a re-circulatory culture system. Survival was maximum

(100%) and minimum (81%) at stocking densities of 200 and 1600 larvae/m3,

respectively. Average weight (66 mg.) was higher in aquaria containing 200

larvae/m3 that for the other stocking densities (44-60 mg.). Specific growth rate

decreased with increased stocking density, survival and growth of larvae were

influenced by water quality, which is regulated by the stocking density of fish.

3.4 MANAGEMENT PRACTICES AFTER STOCKING

Dwivedi et al. (1984) studied the comparative efficiency of the airlift

system in nursery pond management. The growth of common carp fry was

recorded 4.5 to 27.2 mm. and 4.5 to 21.0 mm. respectively, with and without

airlift system ponds in a period of 16 days. The survival was 56.6% in airlift

system pond and 21.3% in without airlift pond. They concluded that

implementation of the airlift system in the nursery management practice

increases the fish seed production. Radheyshyam et al. (1993) studied effect of

phased increased in water level on the survival and growth of Cyprinus carpio

(L.) fry in nursery pond. They reported high survival of 76.6% of fry in

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experimental pond, while in control ponds poor recovery of 25.4% was

recorded. They also stated that average size of fry (25 mm.) in control ponds

was relatively higher compared to experimental ponds (18 mm) probably due to

high density of fry in experimental ponds.

Mondal et al. (2000) evaluated the influence of varying stocking density

on growth and survival of Catla catla fry in nursery cistern. Catla spawn was

stocked @ 2.5 conducted an experiment on intensive rearing of common carp

larvae under indoor flow through system. They conducted the experiment in

three rectangular trays (T1, T2 and T3) connected to each other. Regular flow

rate of 1.5 L/min was maintained. A maximum survival of 79% was registered

in T2 followed by T3 (67.33%) and T1 (65.73%). The overall mean survival

recorded in the study was 70.64%. The growth in terms of individual weight of

larvae was also high in T2 (22 mg) followed by T3 (20 mg.) and T1 (16 mg.).

The mean weight of fry recorded was 19.33 mg.

3.5 GROWTH, SURVIVAL AND PRODUCTION OF FISH SEED

IN REARING PONDS

The results of a case study carried out in 180 hatcheries and nurseries in

northeastern and southwestern Bangladesh over a 30 day period in small-scale

carp hatcheries and nurseries, with special reference to their health

management revealed that three Indian major carps (catla, rohu and mrigal) and

three exotic carps (silver carp, grass carp and common carp) were the dominant

fish species cultured in most hatcheries and nurseries. The average production

for spawn in hatcheries was 844 kg/ha, while in nurseries the production

depended on the size of fry, the average production being 1.722 million /ha.,

1.339 million /ha., respectively, for early fry, fry and fingerlings. Average

survival of spawn, fry and fingerlings in hatcheries and nurseries was

reasonably high, varying between 74-82%. The study indicated that the major

source of spawn for nurseries was hatcheries, while hatchery brood stock were

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mostly collected from the farmer’s grow-out ponds. In general, hatcheries were

more profitable than nurseries. Profitability of nursery operations appeared to

be vulnerable, due the high variability in market price of fry and fingerlings.

Hatcheries and nurseries provided full-time employment to the farmers. The

average contribution of aquaculture to the household income of hatchery and

nursery owners varied between 79.3% (nursery owners) and 95.1% (hatchery

owners). Although hatchery and nursery operations were often family

activities, they also generated employment for hired labour. The major

management problems faced by hatcheries and nurseries were due to disease,

drought and flooding. Diseases were less prevalent in hatcheries than in

nurseries. The major diseases were less prevalent in hatcheries than in

nurseries. The major diseases reported in nurseries were white spot, tail and fin

rot, epizootic ulcerative syndrome, sudden spawn mortality, gill rot, dropsy and

malnutrition, while the major diseases reported in hatcheries were sudden

spawn mortality and fish lice. The economic loss due to disease was about

7.6% of the profit. Gill rot caused highest economic loss to affected farms,

followed by sudden spawn mortality, fish lice, and malnutrition. The results of

this case study indicate that disease is an important issue in hatcheries and

nurseries, although direct economic losses are not significant at this stage and

hatchery and nursery operations are both profitable enterprises (Hasan and

Ahamad, 2002).

A study was conducted to evaluate the potential of floating vertical

raceways for the culture of sunshine bass (female white bass Morone chrysops

and male striped bass m. saxatilis) reared at two densities (125 and 188 fish/m3).

A floating vertical raceway is a system designed to provide a constant,

unidirectional flow of water to fish confined in a flexible raceway that is

suspended vertically in the water column. This study reflected that fish in the

low-density treatment reached a significantly higher final mean weight (160.0 g.)

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than those in the high-density treatment (136.9 g.). Survival was also

significantly higher in the low-density treatment (81.1%) than in the high-

density treatment (73.8%) by Volkman et al. (2004). Influence of management

protocols on carp growth under nursery conditions with relative importance of

food and water quality was studied by Rina and Sharma (1998). Aspects of carp

fry rearing were studied by Kumar (2004) at the Freshwater Fisheries Research

Centre of the Chinese Academy of Fishery Science, Wu Xi, China, during May

to June 2002. Silver carp fry were stocked in an earthen pond. The pond was

fertilized with pig manure and green manure. Water samples were collected

using a plankton sampler at the selected points in the pond. Silver carp fry aged

4 days and having a body length of 10 mm were stocked at a rate of 150 fry per

m2 in the fertilized pond. The pond was harvested and parameters like growth

and survival were recorded. The survival of the fry was 86% in on netting. The

mean length of the fingerlings was 28.8 mm. and the average body weight was

0.21 g. It was concluded that the production of zooplankton following

fertilization could be the major reason for the growth and survival of the young

fry in the nursery pond. Poor growth and survival of common carp larvae due

to differences in type of rearing pond, exchange of water was reported by

Ahmad et al. (2001).

3.6 CARP SEED REARING IN DIFFERENT TYPES OF PONDS

Alikunhi (1966) Categorized carp fish seed of size less than 12 mm.

length and less than 15 mg. weight as larvae. The scientific rearing of larval

phase of carp in manure open nursery ponds is most crucial in the nursery

operation as they are more prone for predation, less responsive for artificial

feeds, susceptible to water quality changes and disease causing pathogens.

Further, exercising control on these factors is very difficult. (Seenappa et al.,

1998) carp seed rearing is carried out in two stages: nursery and rearing, where

the survival of fry is only 30 percent and 50 percent, respectively (FAO, 2007).

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Intensive carp seed rearing in indoor re-circulatory systems, cages and

pens, plastic pools etc., have been attempted by several workers (Alikunhi

1971, 1987; Natrajan et al., 1979; Abraham 1983; Menon 1983; Alikunhi et al.,

1984; Dwivedi, 1987). The potential of floating vertical raceways for the

culture of sunshine bass was evaluated by Volkman et al. (2004) and calculated

that this system offers considerable promise as an alternative rearing system for

deep water impoundments. Intensive rearing of common carp (Cyprinus

carpio) larvae under indoor flow through system was conducted by Seenappa et

al. (1998) with better results over existing system of pond rearing. Cement

cisterns and plastic pools were used for rearing of carp fry by Ariyarathana

(1986). Rearing of common carp fry was conducted in green house during

winter season by Tiwari et al. (2006) and resulted significantly (p < 0.005)

higher production in comparison with open system. Plastic through of 4 × 0.8 ×

0.8 m size were used for rearing of herbivorous fish larvae with better growth

by Wolf et al. (1978). In order to increase seed production, several technologies

have been developed to breed cultivable carps and raise their seed in static

pond systems, cages and pens.

3.7 NATURAL AND ARTIFICIAL FEEDING

Kirk (1972) and Kirk and Howel (1972) have demonstrated that the

survival rate of fish larvae and fry is greatly enhanced if these baby fishes are

maintained on a diet of zooplankton organism instead of artificially formulated

feeds. Lubzens et al. (1984) reported that adding rotifers to diet of carp larvae

increased growth rate and would allow either faster production of carp larvae

from the hatchery, or the use of larger larvae for stocking outdoor ponds. Mok

(1985) carried out an investigation on induced spawning and larval rearing of

the White Sea bream, Mylio berda. The hatched larvae were reared in 500 L

circular tank and initially fed on rotifer, Brachionus sp. followed by

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Brineshrimp naupli or copepod naupli and finally weaned onto fish meat. He

reported average length of 26.2 mm. Sinha and Ramachandran (1985)

described that nursery should have plenty of fish food organism of smaller size

before the hatchlings are stocked. This is important since at that stage the yolk

of the hatching is observed and it starts feeding in nature.

Keshavappa et al. (1990) made comparative study on the survival and

growth of common carp from spawn to fry when fed on soybean flour and

conventional feed mixture of rice bran and groundnut oilcake in fertilized and

unfertilized cistern. In fertilized cistern, they reported an average survival of

60.36% and growth of 6.48±1.83 mg in soybean flour fed cistern, whereas

31.23% survival and 4.74±1.66 mg gain in weight in cistern fed with

conventional feed. In another experiment, where spawn were stocked in

unfertilized cistern, they reported an average survival of 69.76% and growth of

2.35 ± 0.68 mg with soybean flour and an average survival of 33.53% and

growth increment of 1.95±0.58 mg with conventional feed.

Shirgur (1991) explained that rearing of carp spawn into fry needs

continuous provision of suitable zooplankton organism of desired quality and

quantity in the nursery ponds for feeding and growth. In this connection,

intensive studies have shown that optimized rearing of carp fry (up to 20 mm

size) from spawn stage was possible with in a short cycle of 11 days by

adopting phased fertilization technique. Chakrabarti and Jana (1992) compared

the growth of fry fed on zooplankton at 134, 264, and 412 mg/L normal, 2 fold

and 4 fold feeding level, respectively, every other day. There were significant

differences between the normal live feed system and the 2 fold or 4 fold

treatment, but no difference between the letter two treatments. They concluded

that fish production in the 4 fold treatment was not proportionate to the rise in

zooplankton density, and hence, the 2 fold treatment was the most appropriate

for carp growth. Ovie et al. (1993) stated that the absence of the natural fish

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Fig. 7: Acclimatization of fish seed in the pond

Fig. 8: Harvested fish seed

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food organism in a hatchery system, where induced breeding of fish is

practiced, requires that these organisms be harnessed in mixed or pure culture

from the wild and intensively cultured in enclosure to ensure their ready

availability to the young fish larvae and fry.

Jena et al. (1996) conducted an experiment to evaluate the efficiency of

a formulated feed on survival and growth of rohu and catla-rohu fry fed on the

experimental diet showed significant increase in the length and weight at

different stages of the experiment in comparison to the treatment groups fed on

control diet. Mohanty et al. (1996) conducted experiment on rearing of catla

spawn on four formulated diet containing 46.5% each of groundnut oilcake and

rice bran, 5% cod liver oil and 1% each of vitamin and mineral mixture (D -1),

50% goat liver, 21.5% each of groundnut oil cake and rice bran, 5% cod liver

oil and 1% each of vitamin and mineral mixture (D-2), 31.5% each of

groundnut oil cake and rice bran, 30% Bioboost forte and 1% each of vitamin

and mineral mixture (D-3), and 50% goat liver, 30% Bioboost forte, 13%

starch, 5% cod liver oil and 1% each of vitamin and mineral mixture (D-4).

They reported maximum average weight of 53 mg and 97% survival of spawn

on diet (D-4) as compared to 32, 40 and 51 mg average body weights and 77,

81 and 83% survival with diets D-1, D-2 and D-3 respectively.

Chakrabarti and Sharma (1998) tested five feeding scheme under nursery

condition. Live zooplankton cultured outside the fish growing tank (L.F.S.);

direct nursery pond fertilization schedule in static (M.S.) as well as in exchange

water (EMS); intermediate condition between the LFS and MS (IS); and

supplementary food system using mixture (1 : 1) of finely ground mustard oil

cake and boiled rice (SFS). The average weight of carp attained in the LFS was

significantly higher than that in the other four feeding scheme. Plankton intake

by the carp fry was highest in the LFS. The rate of survival was also much

higher in the LFS as compared with the rest of the treatments. The water

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quality remained far better in the former than the latter. Jana and Dutta (1998)

evaluated the growth of common carp fry in different groups in group fed on

artificial plankton diet, on supplemental feed like rice bran and mustard oil

cake and in a group directly fertilized in a tank. The daily grow rate, average

body weight and condition factors were significantly higher in the artificial

plankton fed group as compared to latter two groups. The mean survival

percentage was also higher in artificially plankton fed group to latter two

groups. Better growth in artificial plankton fed group was attributed to higher

dietary values, enzyme content and better water quality parameters.

3.8 RESULTS AND DISCUSSION

The details on length and weight, survival, average weight gain per

month and total number of fingerlings harvested in different ponds on same diet

have been presented in Table 5 and 6.

At the time of stocking the average length was found 25.2, 25.6 and

23.57 mm. in cemented rearing ponds for silver carp, grass carp and common

carp, respectively (Table 3), while it was 24.57, 25.58 and 23.63mm. in

polytanks for silver carp, grass carp and common carp, respectively (Table 4).

These data on initial length were almost similar with slight difference and are

non-significant at analysis of variance. Average initial weight was found 1.35,

1.44 and 1.17g. in cemented rearing ponds and 1.45, 1.36 and 1.25g. in

polytanks for silver carp, grass carp and common carp, respectively with non-

significant difference (Table 3 and 4).

At the time of harvesting the average weight was found as 14.48, 12.85

and 7.42g. in the cemented rearing ponds and 15.5, 14.9 and 7.82g. in

polytanks for silver carp, grass carp and common carp, respectively (Table 5

and 6). Final length at the time of harvesting was recorded as 87.28, 83.7 and

70.9mm. in cemented rearing ponds and 89.53, 86.28 and 76.75mm. in

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55

polytanks for silver carp, grass carp and common carp, respectively. The final

length and weight were significantly different at analysis of variance.

The degree of survival and well being of carp larvae dictate the success

and failure of fish culture. Development of fish farming at the commercial scale

is limited due to difficulties in producing sufficient quality of juvenile and high

mortality at larval stage. Pandey (2005) reported a survival rate of 86.6% in

cyprinid larvae whereas, 74.53%, 42.2%, 80.5% and 44.1% survival rate in

cemented tanks with 1 million/ha density, cemented tanks with 2 million/ha.

density, polytanks with 1 million/ha. density and polytanks with 2 million/ha.

density, respectively, were achieved in the present study. High rate of survival

was found with low density level in both types of tanks, may be due to the

favorable water qualities and abundance of natural food. Mondal et al. (2000)

also found the better growth and survival of Catla catla with low stocking

density. The average survival in cemented tanks was 58.4%, while it was

62.3% in polytanks with 6.67% better survival over the previous one. These

results are almost similar to the findings of Mondal et al. (2000), Radhey

shyam et al. (1993), Saha (1991) and Anon (1984). There is also a significant

difference in net production of fingerlings as 2981 nos. and 3221 nos. with 1

million/ha. density and 3376 nos. and 3531 nos. with 2 million/ha. density in

cemented tanks and polytanks, respectively. Hence, 13.25% more production in

terms of fingerlings counting was achieved with high stocking density. The

over all average fingerlings production was 6.2% more in case of polytanks.

But, the average biomass production per month was controversial as 7.66

kg./month and 8.98 kg./month in cemented tanks and polytanks, respectively

with 1 million stocking density, while it was 7.42kg./month and 8.26 kg./month

in cemented tanks and polytanks, respectively with 2 million stocking density.

This may be due to the better condition and food availability in the tanks of low

stocking density. Over all biomass production was 14.3% more in case of

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56

polytanks. It was also remarkable that the average per month weight gain was

16.8% better with lower stocking density in cemented tanks and it was 19.25

better in polytanks. The average per month weight gain was highest for

common carp followed by silver carp and grass carp. The data of this study

reveal that 1 million stocking density is optimum for better survival, growth

and recovery of fingerlings from rearing ponds in coldwater conditions.

Polytanks are more suitable for rearing of carp fingerlings with better survival

and growth due to the advantage of higher temperature and abundance of

plankton.

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39

Table 3: Stocking details of silver carp, grass carp fry at different stocking densities in seed rearing cemented tanks

(2007- 2008)

RT1 RT-2 RT3 RT4 RT5 RT6 Fish

species No. Avg.

L.

(mm)

Avg.

wt

(g)

No. Avg.

L.

(mm)

Avg.

wt

(g)

No. Avg.

L.

(mm)

Avg.

wt

(g)

No. Avg.

L.

(mm)

Avg.

wt

(g)

No. Avg.

L.

(mm)

Avg.

wt

(g)

No. Avg.

L.

(mm)

Avg.

wt

(g)

Silver

carp

2000 25.7 1.49

2000 25.6 1.48

2000 24.9

1.28 4000 25.1 1.45

4000 24.8

1.30

4000 25.1 1.09

Grass

carp

2000 25.7 1.50 2000 25.1 1.47 2000 24.8 1.30 4000 26.2 1.40 4000 26.0 1.50 4000 25.9 1.47

Total

Number

4000 4000

4000

8000

8000

8000

Stocking

rate

M./ha

1.0 Million/ha 1.0 Million/ha 1.0 Million/ha 2.0 Million/ha 2.0 Million/ha 2.0 Million/ha

Common carp seed was stocked in all below mentioned tanks in the month of March 2007-2008 @ 1.0 Million / ha and

2.0 Million / ha

Common

Carp 4000 23.5 1.19 4000 23.7 1.21 4000 24.5 1.30 8000 22.5 1.00 8000 24.2 1.32 8000 22.7

1.00

57

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40

Table 4: Stocking details of silver carp, grass carp fry at different stocking densities in seed rearing Poly tanks (2008-2009)

RT1 RT-2 RT3 RT4 RT5 RT6

Fish

species No. Avg.

L.

(mm)

Avg.

wt (g)

No. Avg.

L.

(mm)

Avg.

wt (g)

No. Avg.

L.

(mm)

Avg.

wt (g)

No. Avg.

L.

(mm)

Avg.

wt (g)

No. Avg.

L.

(mm)

Avg.

wt (g)

No. Avg.

L.

(mm)

Avg.

wt (g)

Silver

carp

2000 24.1

1.46

2000 24.2

1.40

2000 24.5

1.50

4000 25.0

1.40

4000 24.7

1.50

4000 24.9

1.46

Grass

carp

2000 25.2 1.30 2000 25.9 1.29 2000 25.7 1.38 4000 25.3 1.36 4000 25.8 1.46 4000 25.6 1.36

Total

Number

4000 4000

4000

8000

8000

8000

Stocking

rate

M./ha

1.0 Million/ha 1.0 Million/ha 1.0 Million/ha 2.0 Million/ha 2.0 Million/ha 2.0 Million/ha

Common carp seed was stocked in all below mentioned tanks in the month of March 2008-2009 @ 1.0 Million / ha and

2.0 Million / ha

Common

Carp 4000 23.5 1.18 4000 23.8 1.28 4000 23.8 1.18 8000 23.6 1.26 8000 23.7 1.30 8000 23.4 1.29

58

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59

Table 5: Growth, survival and production of fingerlings in cemented

nursery ponds (2007-08)

Ponds/

Tanks Fish species

Avg.

initial

length

(mm)

Avg.

final

length

(mm)

Avg.

initial

wt. (g.)

Avg.

final

wt.

(g.)

Avg.

growth

rate (g./

month

Survival

(%)

Fingerling

Production

RT-1 Silver carp

Grass carp

Common carp

25.7

25.7

23.5

90.7

84.2

70.1

1.49

1.50

1.19

16.4

13.8

7.4

2.48

2.05

3.10

68.3 2732

RT-2 Silver carp

Grass carp

Common carp

25.6

25.1

23.7

91.3

85.6

72.0

1.48

1.47

1.21

16.5

14.2

7.8

2.50

2.12

3.29

81.6 3264

RT-3 Silver carp

Grass carp

Common carp

24.9

24.8

24.5

88.5

84.7

71.7

1.28

1.30

1.30

15.8

14.5

8.1

2.42

2.20

3.4

73.7 2948

RT-4 Silver carp

Grass carp

Common carp

25.1

26.2

22.5

83.5

82.8

70.3

1.45

1.40

1.00

12.8

11.2

7.0

1.89

1.63

3.00

41.8 3344

RT-5 Silver carp

Grass carp

Common carp

24.8

26.0

24.2

84.2

81.1

70.5

1.30

1.50

1.32

12.8

11.6

7.2

1.91

1.68

2.94

40.3 3224

RT-6 Silver carp

Grass carp

Common carp

25.1

25.9

22.7

85.5

83.8

70.8

1.09

1.47

1.00

12.6

11.8

7.0

1.91

1.72

3.10

44.5 3560

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60

Table 6: Growth, survival and production of fingerlings in poly tanks

(2008-09)

Ponds/

Tanks

Fish species Avg.

initial

length

(mm)

Avg.

final

length

(mm)

Avg.

initial

wt.(g.)

Avg.

final wt.

(g.)

Avg.

growth

rate (g./

month)

Survival

(%)

Fingerling

Production

RT-1 Silver carp

Grass carp

Common carp

24.1

25.2

23.5

91.5

88.4

78.2

1.46

1.30

1.18

17.5

14.7

7.8

2.67

2.23

3.31

82.8 3312

RT-2 Silver carp

Grass carp

Common carp

24.2

25.9

23.8

96.6

90.0

78.5

1.40

1.29

1.28

17.6

15.0

7.9

2.70

2.28

3.31

78.3 3132

RT-3 Silver carp

Grass carp

Common carp

24.5

25.7

23.8

94.3

87.1

78.8

1.50

1.38

1.18

16.9

15.6

8.6

2.56

2.37

3.71

80.5 3220

RT-4 Silver carp

Grass carp

Common carp

25.0

25.3

23.6

85.7

83.9

78.6

1.40

1.36

1.26

13.6

12.4

7.6

2.03

1.84

3.17

42.4 3392

RT-5 Silver carp

Grass carp

Common carp

24.7

25.8

23.7

85.0

84.3

74.1

1.50

1.46

1.30

13.6

12.8

7.6

2.01

1.89

3.15

44.8 3584

RT-6 Silver carp

Grass carp

Common carp

24.9

25.6

23.4

84.1

84.0

72.3

1.46

1.36

1.29

13.8

12.9

7.4

2.05

1.92

3.05

45.2 3616

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