Observations on captive breeding of the threatened freshwater shark Wallago attu (Bloch & Schneider, 1801)

Abstract

Juveniles of the threatened freshwater shark Wallago attu procured from a local village pond were successfully reared to brood size under captive conditions in an earthen pond of 0.09 ha, wherein they attained full maturity. The farm reared brooders were successfully induced bred by sGnRH analogue and dopamine antagonist in circular spawning tank of carp hatchery, provided with artificial substratum, wherein spawning took place naturally. Fecundity estimated was 40,000 eggs kg-1. Fertilisation rate was 85±5% and the hatching rate was 90%. Eggs hatched out in 14 - 18 h at 28±1oC. The yolk-sac larvae exhibited severe cannibalism even from one day post-hatch. The larvae were reared for 10 days in FRP tanks on composite diets of plankton, egg custard and carp spawn with 15% survival.