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 (Hermetia illucens) 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 goldfish (Carassius auratus) juveniles. Six isonitrogenous and isoenergetic diets were formulated with BSFLM to substitute FM protein at 0 (T0), 20 (T20), 40 (T40), 60 (T60), and 80 (T80), and 100 % (T100). Each diet was randomly assigned to triplicate groups of 20 fish (Mean weight: 2.8±0.3 g) per aquaria were fed twice a day. Goldfish juveniles fed the T60 diet exhibited maximum growth and feed utilization. However, escalating the percentage of fishmeal substitution with BSFLM above 60 percent led to a significant reduction in growth and feed utilization. The protease activity and the haemoglobin (Hb) value were high in fishes fed with the T60 diet. The MyoD was upregulated in fish fed T40 and T60 diets, while the myostatin was downregulated in fish-fed T40 and T60 diets. Thus, the fishmeal protein substituted at 60% with BSFLM with an inclusion level of 201 g/kg of diet will be suitable for the goldfish juveniles.