AQUAPONIC’S IDEAL FISH

Although there is no ideal fish for Aquaponics, some fish are more sutied to Aquaponics than others.  A lot of what determines what fish an individual may choose is determined by what is needed or desired of the fish.  The following list contains the desirable biological and economic attributes when selecting the best fish. The fish species should:

  • be capable of reproducing in captivity;

  • produce numerous and hardy eggs and young;

  • have well-known culture requirements;

  • be adaptable to many types of culture systems;

  • be adaptable to multi-species farming (polyculture);

  •  exhibit rapid growth to a large maximum size;

  • readily adapt to artificial feeds;

  • be tolerant of crowding and high density conditions;

  • exhibit high survival (low mortality) rates;

  • be easy to handle, harvest, and transport;

  • be resistant to disease and parasite infestations;

  • not be cannibalistic or territorial;

  • be readily available as eggs, fingerlings, and adults;

  • have a high market demand;

  • exhibit high feed conversion rates;

  • have good dress-out weight values;

  •  have a long shelf life;

  • be easy to process;

  • have a healthy appearance and color;

  • have good eating qualities or high resale value in pet trade;

Tilapia

SPAWNING HABITS

Spawning occurs when the water temperature exceeds 68F. Males dig large circular nests with their mouths in shallow water over a sandy bottom. The male swims out to a passing female and leads her to the nest where courtship occurs; female lays eggs and immediately takes them into her mouth after male fertilizes, after which she swims off.

The males continue to guard nests and may spawn again with another female. Eggs hatch in female’s mouth, and fry are occasionally released to feed, but whenever threatened they return to the female’s mouth until they are about three weeks old. This type of parental care is called mouth-brooding.

FEEDING HABITS

Feed primarily on plankton and small organisms living in or on bottom detritus; most common foods in the wild are detritus, algae, diatoms, and plant material.

AGE AND GROWTH

Grow rapidly for first few months, then slow somewhat but ultimately reach 5-6 pounds by age 3-5 yrs; fish weighing 2-4 pounds common; males being larger at each age than females.

EDIBILITY

White flaky meat with a mild flavor; considered excellent eating, and farm-raised fish often sold in grocery stores.

SPECIAL NOTE

Possession and transport of live tilapia in Florida is illegal without a special permit (except blue tilapia). They can only be possessed if dead, so anglers who catch and want to eat a tilapia, other than blue tilapia, should immediately place them on ice.

Channel Catfish

SPAWNING

Channel catfish can be sexually differentiated at about 6 months of age and normally breed for the first time in their second or third year of life. Thereafter, catfish will usually spawn every year throughout their life time The spawning season of channel catfish is usually during the months of April through June; females start laying their eggs at water temperatures above 21°C (70°F). The eggs of channel catfish are large (2.4-3.0 mm or 0.1 inches in diameter), very adhesive, and usually laid in a large egg mass.

Females have large variation in the number of eggs they produce, laying between 3,000 and 50,000 eggs, depending on the age and size of the fish; improved spawning success (number of eggs produced, larger eggs, and egg fertility) are observed in fish three to five years of age. Catfish have an elaborate breeding behavior and the male usually incubates the eggs.

The period of incubation (hatching time) of catfish eggs depends on water temperature.ggs hatch in four to ten days at temperatures between 21 and 27°C (70-81°F); at optimum spawning and incubation temperatures (25°-27°C), embryos hatch in 4 to 6 days. Young absorb their yolk sacs and begin swimming (swim-up stage) 3-4 days after hatching. After yolk absorption, young catfish actively feed on a variety of foodstuffs and readily accept artificially prepared diets.

PRODUCTION REQUIREMENTS

Most of the farm-raised catfish are cultured in ponds constructed with levees. Average pond size is 7.1 water hectares (17.5 acres) on 8.1 hectares (20 acres) of land. Although this large size pond is less expensive to construct, it is more difficult to manage; pond sizes between 5 and 10 acres are preferable. Catfish are also raised in watershed ponds, and in high-density culture systems that make use of tanks, raceways, and cages. Raising channel catfish mixed with other species of fish (polyculture) is also practiced.

WATER REQUIREMENTS

Regardless of the production system employed, efficient production of channel catfish requires a dependable supply of large volumes of water. For example, in pond production at least 185-280 l/mm of water per hectare of pond surface (20-30 gpm/ acre) are essential. For intensive fish production in raceways, 5.7-7.6 m 3 /min (about 235 ft 3 /min) of water are necessary.

NUTRITION

Channel catfish are efficient food converters and will gain between 0.45 and 0.67 g of body weight per gram of food consumed (e.g 1.5-2.2 lbs of feed/1lb of fish). Growth of channel catfish to fingerling and edible size is influenced by a variety of factors. Water temperature, quality of the diet, feeding rate, age of fish, and stocking density noticeably affect the growth rate of the fish. Catfish require a well-balanced diet which is high in protein and energy. Dietary requirements, however, are based on differences in age, size, water temperature, natural food availability in the pond, daily feed allowance, and stocking density of fish.

Recommended dietary levels of crude protein vary from 25 to 36%, based primarily on quality of the dietary protein and amount of non-protein energy in the feed; starter diets for young fry should contain 36 to 40% crude protein. Supplemental energy in catfish diets is provided by high quality lipids (fats) at levels between 3 to 16% of the total diet. From a practical view point, however, lipid levels in catfish feeds are kept below 6%. Catfish can utilize a wide variety of types and amounts of carbohydrates in their food, so their levels are usually formulated at the least cost of the diet. Vitamins and minerals are an essential dietary requirement for channel catfish.

Because of the small amounts required and susceptibility to degradation, catfish feeds are supplemented with vitamin and mineral pre-mixes. The daily feed ration for channel catfish is affected by a variety of factors. The amount of feed provided depends on water temperature, fish size, and water quality. Newly-hatched fry should be fed several times daily at 6-10% of fish weight. The daily feed ration for fingerling and brood fish catfish should be divided into two or more feedings per day. In general, fingerlings are fed between 2 and 5 percent of their body weight per day, and brood fish, 1 to 2% of their weight.

STOCKING & DENSITIES

Fish yields and stocking densities for channel catfish are extremely variable and vary according to system of production used, level of management, and size and number of fish desired at the end of the growing season. The average yield of a fed and aerated production pond is around 4,000 kilograms of catfish per hectare of water (3,500 lbs/acre/year); by multiple harvesting (when fish are periodically graded and harvested) yields of 5,000-6,000 kg/ha/ year (around 4900 lbs/acre/year) can be obtained. When raising catfish in floating cages, yields of 275 kg of fish per cubic meter (17 lbs/ft 3 ) have been recorded.

Young fry are stocked primarily depending on the size and quantity of fingerlings desired at harvest; stocking densities from 20,000 to 70,000 fry per hectare (average 18,211 fry/acre) are common. In final grow out ponds, fingerling (10-50 g) stocking rates average around 8,500-10,000 fish per hectare (3,743 fingerlings/acre). In multiple harvest production systems, up to 24,000 fish per hectare (9,713 fish/acre) are reported. In net enclosures, stocking densities for 15-20 cm (6-8 in.) long catfish fingerlings range from 212 to 424 fish per cubic meter (6-12 fish/ft 3 ) of cage.

Net pens are usually arranged in open patterns to allow sufficient water circulation through them. When suspended in ponds, total fish stocking densities inside the cages cannot exceed those numbers which would be achieved by growing the fish free-swimming in the pond. The time required to raise channel catfish to market size is primarily dependant on water temperature, age of fish, fish density, quality of diet and level of feeding. Estimated time to raise channel catfish from egg to food-size fish is between 15 and 18 months. In northern Florida, 7 to 9 months are necessary to raise 10-20 cm (4-8 in.) long fingerlings to around 453 grams (1 lb).

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