Dietary protein replacement of fish meal with black soldier fly larvae meal: Effects on growth, whole-body composition, digestive enzyme activity, muscle-growth-related gene expression and haemato-biochemical responses of juvenile goldfish, Carassius auratus

A 60-day indoor growth trial was carried out to investigate the effects of dietary replacement of fish meal (FM) protein with black soldier fly larvae meal (BSFLM) at graded concentrations on bio-growth parameters, whole-body chemical composition, digestive enzyme activity, muscle-growth-related gene expression and haemato-biochemical responses of goldish juveniles ( Carassius auratus ). Six isonitrogenous and isoenergetic diets were formulated with BSFLM to substitute FM protein at 0 (T0), 20 (T20), 40 (T40), 60 (T60), 80 (T80) and 100 percent (T100). The aquaria with 20 fishes in each replicate were fed with experimental diet twice a day. Gold fish juveniles fed T60 diet exhibited maximum growth performances and feed utilization. However, escalating the percentage of fishmeal substitution with BSFLM above 60 percentage led to significant reduction in growth and feed utilization of goldfish juveniles. The protease activity was high in T60 and T80, wherein the lipase and amylase activity were high in T100. The relative mRNA expression of GH and MyoD was significantly upregulated in fish fed T40 and T60 diets, while the myostatin was significantly downregulated fish fed T40 and T60 diets. Thus, the fishmeal protein substituted at 60 percent with BSFLM with an inclusion level of 20.1 g/kg of diet will be well suitable for the goldfish juveniles.