Effect of Fermented Plant Protein on the Growth of Juvenile Mud Catfish (Clarias gariepinus) in Imo State

This study examined the effects of fermented plant protein (soybeans fermented using Bacillus subtilis) as a replacement for fishmeal in the diets of juvenile African mud catfish (Clarias gariepinus) in Imo State, South East Nigeria. High fishmeal costs represent one of the most significant constraints to catfish aquaculture profitability in Nigeria, and fermentation has been shown to improve plant protein digestibility and reduce anti-nutritional factors. Five experimental diets were formulated with fermented soybean meal replacing fishmeal at 0, 25, 50, 75, and 100 percent inclusion levels. Juvenile catfish with a mean initial weight of 8.3 grams were distributed across 25 experimental tanks and fed twice daily over a ten-week culture period. Feed conversion ratio, weight gain, specific growth rate, protein efficiency ratio, and survival rate were assessed bi-weekly. Results showed that fish fed diets with up to 75 percent fermented soybean meal substitution maintained growth performance comparable to the control fishmeal-based diet, with no statistically significant difference in specific growth rate. Complete replacement at 100 percent resulted in significantly reduced growth and increased feed conversion ratio. Liver histology revealed no pathological changes at inclusion levels up to 75 percent. Economic analysis confirmed that diets with 75 percent fermented soybean meal substitution reduced feed costs by 32 percent relative to the control. The study recommends the commercial application of fermented soybean meal at up to 75 percent fishmeal replacement in juvenile catfish diets in Imo State and similar production contexts. Keywords: fermented soybean meal, fishmeal replacement, Clarias gariepinus, aquaculture nutrition, Imo State