Hatcheries
used in producing catfish are simple facilities that use flow-through
tanks holding about 90 to 100 gallons of water for egg incubation and
fry rearing. The most critical factor for a successful hatchery is a
dependable supply of high-quality water. Egg hatching tanks are equipped
with a series of paddles spaced along the length of the tank to allow
wire-mesh baskets to fit between them. One or two egg masses are placed
in each basket and the paddles gently rotate through the water to
provide water circulation and aeration. The incubation time varies from 5
to 8 days depending upon water temperature. At hatching, the fry
(called sac-fry at this point) fall or swim through the wire-mesh
basket and school in tight groups.
Sac-fry
are siphoned into a bucket and transferred to a fry rearing tank.
Aeration in fry rearing tanks is provided by surface agitators or by air
bubbled through airstones. Initially, sac-fry are not fed because they
derive nourishment from the attached yolk sac. Over a 3- to 5-day period
after hatching they absorb the yolk sac and turn black. At that time
fry (now called swim-up fry) swim to the water surface seeking food.
Swim-up fry must be fed 6 to 12 times a day for good survival and
growth. Fry are fed nutritionally complete feed for 2 to 7 days before
they are transferred to a nursery pond. Fingerling Production Culture
practices for fingerling production are relatively standardized across
the industry, especially when compared to the wide variety of production
strategies used to grow food-sized catfish. Fry grow faster when
stocked at lower densities but more space is required to grow larger
fingerlings at lower densities.
Stocking
rate is therefore a compromise between benefits of producing large
fingerlings for food fish growout and the economics of producing more
small fingerlings in less space. Fish are fed a manufactured feed and
grown to fingerling size (3 to 8 inches long) over a 5 to 10 month
period. Fish are either allowed to continue growing in their original
nursery ponds or are harvested and transferred to other ponds for
growout to stocker-sized fish of 0.1 to 0.25 pounds or to food-sized
fish of 1.2 to 2.5 pounds. It is important to fertilize nursery ponds so
that they contain abundant natural foods to promote growth until the
fry are large enough to switch to manufactured feeds. A finely ground
feed should be offered once or twice daily to train fish to accept the
feed.
As
the fish grow, feed particle size is increased. A month or so after
stocking, the fish (now called fingerlings) are fed once or twice daily
to satiation, using a small floating pellet with 45 to 65 percent crude
protein. Because fingerling populations are particularly susceptible to
infectious diseases, disease management takes on added importance in
this stage of production. Survival of catfish fry to fingerlings varies
greatly from pond-to-pond depending on the initial condition of the
nursery pond, losses to bird predation, and the incidence of infectious
diseases. Average survival from fry stocking to fingerling harvest in
excess of 60 percent across all ponds on the farm is considered to be
very good.
FOR ULTRA MODERN HATCHERY SETUP, FISH FARMING SETUP, FEED PRODUCTION AND FEASIBILITY STUDY
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