Effect of silkworm (Bombyx mori) pupae on the growth and maturation of Rainbow shark Epalzeorhynchos frenatum (Fowler, 1934) under captive rearing

Abstract

The aim of this study was to determine the impact of replacing fishmeal with silkworm pupae (Bombyx mori) meal in the diet of rainbow shark Epalzeorhynchos frenatum (Fowler, 1934), on growth and maturation. Four isonitrogenous and isocalorific experimental diets (35% CP) were prepared using silkworm pupae (SWP) replacing fish meal at three different levels viz., 30% (T1), 40% (T2) and 50% (T3) and diet with only fish meal served as control (C). The experimental trail was conducted in hapas, in duplicates, installed in an earthen pond. The fish (average weight - 1.4 g and total length - 5.24 cm) were stocked @10 nos. per hapa. During the experimental period, water quality parameters were monitored routinely. The experimental diets T1, T2 and T3 performed significantly better than diet C (control) in terms of growth performance. Among the four diets, T1 showed significantly higher weight gain (5.18±0.28 g), specific growth rate, SGR (2.54±0.07% day-1), protein efficienvy ratio, PER (1.50±0.04) and food conversion ratio, FCR (1.91±0.06) compared to other treatment groups. Among all the diets, highest gonadosomatic index, GSI (14.90%) was obtained in fish fed diet T1. At the end of the experiment, all the experimental diets fed fishes showed similar stages of maturity, late vitellogenic stage. Overall, the results of the present study conclude that SWP can be used as a low-cost animal protein to replace fish meal upto 30% in the diet.

Keywords: Fish meal replacement, Low cost ingredient, Maturational diet, Ornamental fish diet, Rainbow shark, Silkworm pupae