Fish meal is scarce and expensive; therefore, there is a search for cheaper alternatives that promote fish growth without compromising physiological functions. African palm weevil (Rhynchophorus phoenicis) larvae, which contain approximately 63% crude protein, may serve as a suitable alternative. Defatting the larvae increases protein levels, maintains a good amino acid profile, boosts mineral content, and reduces oil content, making it an excellent option for producing low-fat food fish. This study, therefore, investigated the effects of partially replacing fish meal with defatted palm weevil larvae meal in the production of African catfish, Clarias gariepinus.
African palm weevil larvae were procured from a commercial vendor, defatted, and blended into a fine semi-powder to create a meal. This meal was used to replace fish meal at 0, 20, 30, 40, and 50% in the diets provided to African catfish juveniles. Feeding continued for 56 days, after which biometry was conducted. Samples of fish from each treatment were randomly collected to determine carcass values and various biochemical profiles of the fish.
Results indicated no significant differences in mean weight gain and specific growth rate between fish fed 100% fish and those fed diets containing up to 50% defatted palm weevil larvae meal (Table 1). Carcass analyses also revealed similar (P > 0.05) characteristics in protein deposition, ash composition, and carcass lipid. However, carcass lipid decreased slightly with increasing levels of defatted palm weevil meal in the diets. Furthermore, the biochemical profile showed that dietary palm weevil increased superoxide dismutase and total protein while reducing alanine aminotransferase and aspartate aminotransferase. In conclusion, defatted palm weevil larvae could replace up to 50% of fish meal in the diets of African catfish.