Cannibalism, a cause of high mortality in Wallago attu (Schneider) larvae

A study was conducted to find the effect of stocking density on bio-growth, specific growth rate, percent weight gain and survival of Wallago attu larvae during in-door larval rearing. The larvae of average weight 2.64 + 0.21 mg and length 5.80 + 0.36 mm were stocked at a density of 2,4,6,8 and 10 nos/l and reared by feeding live zooplankton, for a period of 10 days. The final body weight, specific growth rate and percent body weight gain of larvae was influenced significantly (P<0.05) by stocking densities and highest performance was observed in fish stocked at 10 nos/I. The percent survival of larvae decreased significantly with increase of stocking density and the rate of survival was similar among 6nos/I - 10 nos/I groups. The loss of larvae was observed due to cannibalism during rearing. The lowest stocking density resulted in least cannibalism. Systematic approach and some anatomical feature of W. attu larvae are beleived to be helpful for predation during rearing.