WARM-FRESHWATER AQUACROPS[objectives]
• Describe general environmental requirements for warm-freshwater species
• Discuss the production of catfish, crawfish, prawns, tilapia, striped bass, and other finfish species
GENERAL REQUIREMENTS FOR WARM-FRESHWATER SPECIES
• Temperature range of 70o to 90o F.
• Species grown in tanks in greenhouses where the water can be kept warm year-round are not affected by seasonal changes
PRINCIPLES OF SPECIES SELECTION
• Select only a species adapted to the production system to be used.
• Bryant HS already had greenhouses before we decided to grow redclaw crawfish
• Therefore we could control both the air and water temperatures to grow this tropical species year-round
CATFISH
• Catfish production leads all freshwater aquacrop production in the U.S.
• Predominant species are the channel catfish, blue catfish, and white catfish
• Genetically improved and hybrid catfish are increasingly being grown
CHANNEL CATFISH
BLUE CATFISH
WHITE CATFISH
HYBRID CATFISH
ENVIRONMENT REQUIRED
• Optimum temperature 75 – 85o F
• Stop feeding when temperature is above 95o F or below 60o F
• Will grow in ponds, streams, raceways, or other water facilities
• Dissolved oxygen kept above 4 mg/L
• pH range 6.3 – 7.5
SEEDSTOCK
• Natural spawning – cavity spawners; lay eggs in hollow logs and stumps
• Farm spawning – use spawning containers such as milk cans, boxes, etc.
SEEDSTOCK
• Hatching – either hatch naturally or in hatchery
• Needs moving water (not flowing) at temperature of 75 – 85o F
• Hatching occurs in 6 – 10 days• Newly-hatched fry live off egg sac for
several days• Fine meal feed is used for next several
weeks
HATCHING CATFISH
CULTURE, STOCKING, AND FEEDING CATFISH
• Stocked as 5 – 8-inch fingerlings • Stocking rates vary from 2000 – 5000 per
acre• Typically fed floating feed that is 28 to
32% protein• Should be fed 1 – 2 times daily• Fingerlings are fed 10% of body weight
daily, fish under one pound need 3% daily, and fish over one pound need 2% daily
STOCKING AND FEEDING
HARVESTING CATFISH
MARKETING CATFISH
• Broodfish may be sold to hatchery operators
• Hatcheries produce eggs, fry, and fingerlings
• Grow-out farmers stock ponds with fingerlings and grow them as food
• Recreational fee-lake operators buy from growers to stock out their ponds
CRAWFISH
ANATOMY
MOLTING (ECDYSIS)
• Crawfish have hard shell which must be shed to grow
• Calcium is extracted from shell and stored in glands while molting
• After shedding old shell, body uptakes water and expands 20%
• New shell hardens within 12 hours• Crawfish molts about 12 times before it
reaches maturity
MOLTING
REQUIRED ENVIRONMENT
• Naturally found in shallow, weedy swamps and ponds
• Prefer water temps between 65 to 85oF
• Dormant below 45oF
• Range of pH 5.8 to 8.2
• Redclaw are tropical and die at temps below 50oF
CRAWFISH PONDS
SEEDSTOCK
• Burrowing – crawfish dig holes (burrows) for shelter and reproduction
• Mating – male deposits sperm packet on female in late spring (redclaws can mate up to 3 times annually)
• Hatching – eggs (200 – 800) are attached to underside of abdomen and hatch in 14 – 21 days (30 – 40 days for redclaw)
GRAVID RED SWAMP CRAWFISH
GRAVID REDCLAW
FEEDING
• Crawfish are omnivorous and feed mainly on detritus (decaying bits of plants and animals)
• Red swamp crawfish forage on rice stubble
• Commercial crawfish feeds are often used as supplemental feed
DISEASES AND PREDATORS
• Very few diseases cause problems with crawfish (bacterial and fungal)
• Crawfish can be infested with zebra mussels
• Common predators are trash fish, birds, raccoons, frogs, snakes, turtles, and water beetles
DISEASES AND PREDATORS
HARVESTING AND MARKETING
• Red swamps are harvested in winter and spring with baited traps
• Crawfish are sold alive for boiling or tails may be peeled and frozen
• New market niches are developing for softshell crawfish
HARVESTING AND MARKETING
FRESHWATER PRAWNS
• River prawn Macrobrachium rosenbergii
• Tiger prawn Panaeus esculentaus
• Pacific white shrimp Panaeus vannemai
• Grown in low salinity water (<5 ppt)
• Water temps 75 to 85oF
• Grown in earthen ponds outdoors and lined ponds in greenhouses
Macrobrachium Tiger prawn
Pacific white shrimpShrimp farm
SEEDSTOCK
• Females produce about 28,000 eggs per ounce
• Eggs hatch in 20-21 days and must be fed plankton
• Larvae swim upside down and backwards
• Reach postlarvae stage (stocking size) in 15 to 45 days
Nauplius
Zoea
Mysis
TILAPIA
• Most widely raised warm-freshwater fish in the world
• Tilapia first cultured 4000 years ago in Africa
• Most common species cultured include Java, Zanzibar, blue, and Nile tilapia (all four are mouth-brooders)
Java Zanzibar
Blue Nile
CULTURE
• Tilapia are tropical and must be kept above 50oF (80 to 90oF is ideal)
• Tolerate low oxygen, high ammonia, and other conditions that would be lethal to many species of fish.
• Spawning is easy; the problem is usually overpopulation
• Tilapia naturally feed on plants, insects, detritus, and plankton
STRIPED BASS
CULTURE
• Can grow in freshwater, brackish water, or saltwater (most commercial production in freshwater)
• Grow best at 77 to 88oF (survive down to 40oF)
• Specialized hatcheries needed for seedstock production
• Stocked 1000 to 4000 per acre• Need feed 35 to 45% protein
OTHER FINFISHbluegill redear
warmouth