Effect of replacement of dietary fish meal with silkworm pupae meal and black soldier fly larvae meal as a combination diet on the growth and digestive performance of koi carp Cyprinus carpio var. koi in the nursery phase

The feasibility of using silkworm pupae meal and black soldier fly larvae meal in combination to replace fish meal in koi carp fry was assessed. Two weeks-old koi fry (2.47 +/- 0.15 cm, 0.28 +/- 0.06 g) were used as experimental animals. Four iso-nitrogenous experimental diets (T1, T2, T3, T4) with 35 +/- 0.37% crude protein were formulated. In T1, T2 and T3, 50% of fish meal was replaced with silkworm pupae meal and black soldier fly larvae meal at different combinations, i.e., T1 (25:75), T2 (50:50), T3 (75:25). In T4, 100% of fish meal was replaced with silkworm pupae meal and black soldier fly larvae meal at 50:50 ratio. Present research findings showed that T2 diet-fed fishes performed significantly better (p<0.05) than other diets in all the growth parameters viz., mean length gain (3.13 +/- 0.01 cm), mean weight gain (3.13 +/- 0.02 g), percentage length gain (127 +/- 0.71%), percentage weight gain (1118 +/- 7.07%), specific growth rate (4.16 +/- 0.01%/day), feed conversion ratio (1.30 +/- 0.01), feed efficiency ratio (0.76 +/- 0.01), protein efficiency ratio (2.18 +/- 0.01) and survival rate (28 +/- 1.41%). Digestive enzyme activities were also higher in T2 diet-fed fishes. Therefore, insect meal can be effectively utilised to replace fish meal in the diet of koi fry.