The production of eggs in catfish presents few problems as the as the fish will spawn in farm ponds. In North America catfish spawn using one of three different systems:either in a pond in which has been placed a container suitable for a nest site; or in a pen constructed in the pond; or by induced spawing in a hatchery tank. In pond spawning, paired catfisch are left in the pond which contains a suitable nest area and are in which they can spawn. Spawning ponds are about 1/4ha in area and are Stocked at s density of between 50 to 300 fish per ha. In pen spwaning each pair of fish is confined with a suitable spawning container in a wire mesh pen 3 to 6m2 and 1m deep.
Regularly, In both systems the eggs may be left to hatch in the pond or may be removed for hatching in hatchery. Spawning in a hatchery tank is induced by injecting the females with three doses of acetone dried fish pituitaries with an average weight of 10mg, or with one dose of human chlorionic gonadotropin, containing 60 to 2,200 Intertional Units; the males are not injected. The resultant eggs are hatched in the hatchery. Femals lay between 3,000 and 20,000 eggs depending depending thier egg size.
In case of the pangasiidae and clariidae a high proportion of the seed is obtained from the wild as fry. However some induced spawing is now carried out in Thailand. Clariidae will also spawn in farm ponds. Eggs are hatched in simple hatcheries consisting of troughs of running water inwhich the egg masses are placed, egg masses being kept in motion in the water by means of mechanical agitators.
Ictaluridae eggs hatch in 5 to 10 days at 20c and the eggs of pangasiidae in 1 to 3 days at 28c.
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