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