Influence of certain environmental factors on the predatory efficiency of the larvivorous fish Macropodus cupanus

Abstract

Investigations of the effect of certain environmental factors on predatory efficiency of the indigenous larvivorous fishMacropodus cupanus indicates the dependence, in a quantifiable way, of predation on the environmental complex surrounding the prey-predator system. Prey consumption is less at low temperatures and increases significantly with rise in temperature. Feeding under conditions of light is significantly higher than in darkness. Salinities of up to 21.83 do not affect predation rate, except that owing to stress conditions, prey intake at 21.83% is lower than at 0.12%. Considering fish size, in terms of unit body weight, predation declines significantly as size increases. However, when total body weight is considered, predation increases with increase in fish size. Environmental factors do not alter the time course of predation regularly or significantly, perhaps owing to haphazard intake subsequent to satiation and/or a learning factor. The higher predation rate of this fish when compared to the conventional larvivoreGambusia affinis indicates its potential as a biocontrol agent of mosquito larvae.