A 12-week trial assessed replacing fishmeal (FM) with defatted black soldier fly larvae (BSFL) and soy protein (SOY) in African catfish Clarias gariepinus diets. Six hundred juveniles were fed five diets: control (100% FM) and 25%, 50%, 75%, and 100% FM replacement with BSFL and SOY (triplicates).
Fish fed 25% replacement showed growth similar to control, while 75% and 100% replacements reduced growth (Figure 1). Feed efficiency was highest at 25% and 50% replacement. Key physiological and biochemical markers, including hepatosomatic index, plasma alanine aminotransferase, IgM, total iron-binding capacity, and cortisol, varied significantly with diet (Table 1). The 50% replacement diet had the highest IgM; cortisol and iron-binding capacity increased at higher replacements.
Immune and growth gene expression was influenced by BSFL and SOY, with 50% replacement upregulating IGF-I and IgD, and 100% replacement increasing pro-inflammatory IFN-γ.
Values marked with * are significantly different (P < 0.05) from the control group.
Defatted BSFL and SOY can replace up to 50% of fishmeal without harming growth or health, supporting their use as sustainable fishmeal alternatives.