Utilization of an insect-based diet by a herbivorous fish (Oreochromis mossambicus) and an opportunistic predator (Clarias gariepinus)

Abstract

An 8-week feeding trial was conducted to evaluate the effect of Alates termite (Macrotermes falciger) based diet in a herbivorous (Oreochromis mossambicus) and an opportunistic predator (Clarias gariepinus). Five diets were formulated to replace fishmeal at 0, 10, 30, 50, and 70 % and were denoted D1, D2, D3, D4, and D5, respectively. Clarias gariepinus sub-adults (209.24 ± 2.41 g/fish) were stocked at 5 fish per tank in recirculating fibreglass tanks (400 L) in triplicates. Oreochromis mossambicus juveniles (7.4 ± 4.78 g/fish) were randomly stocked at 10 fish per tank in recirculating fibreglass tanks (400 L) in triplicates. Fish were fed their allocated diets, twice a day to apparent satiation. Growth performance indices (specific growth rate, thermal-unit growth coefficient) were lowest at inclusion level above 50 % in both species (P < 0.05). The nutrient utilization indices (feed intake, protein efficiency ratio) were lowest at inclusion level above 50 % in both species. The organosomatic indices (condition factor, hepato-somatic index, viscero-somatic index) were not influenced by the inclusion of Alates termite meal in both species. The aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were not influenced by Alates termite meal in O. mossambicus (P > 0.05). However, AST and ALT levels significantly increased at inclusion levels above 50 % in C. gariepinus (P < 0.05). The triglyceride, cholesterol, and glucose levels showed no significant difference across diets in both fish species (P > 0.05). The study showed that both species may utilize an insect-based diet up to 50 % inclusion levels without adverse effects on growth performance and nutrient utilization.