House cricket (Acheta domesticus) as a modulator of gene expression in digestion and oxidative stress in the redhead cichlid (Vieja melanura) (Günther, 1862)

Cricket meal (Acheta domesticus), an accepted protein source for fish feed, is an excellent nutritional alternative to fishmeal in aquaculture. This study evaluated the effects of cricket meal inclusion in the diet of the redhead cichlid (Vieja melanura) on growth and the expression of genes related to protein digestion and oxidative stress. Five experimental diets were formulated with 0, 25, 50, 75, and 100% cricket protein inclusion as a substitute for fish meal (FM). Two hundred twenty-five fish (0.17 ± 0.01 g) were fed for 45 days at a rate of 5% of their biomass under controlled conditions. Biometric measurements were taken every 15 days. At the end of the experiment, final biometric data were recorded, and organs and tissues were collected to evaluate gene expression by qPCR using the elongation factor 1 (ef-1) gene as a reference. Results showed higher absolute weight gain at T25 and higher specific growth rate at T25 and T50, while feed conversion ratio and protein efficiency ratio were negatively affected at T100, compared with T0. Pepsin was overexpressed in the T25, T50, and T75 groups; trypsin in the T25 group; and chymotrypsin in the T25 and T50 groups. Regarding oxidative stress, the liver showed the highest antioxidant gene expression, with superoxide dismutase overexpressed from T50 onward, glutathione peroxidase only at T50, glutathione S-transferase at T25, T50, and T75, and catalase overexpressed at T100. We conclude that the optimal FM replacement level with house cricket meal in V. melanura is 50%. Higher inclusion levels compromise its growth, health, and well-being.