Tenebrio molitor and Hermetia illucens Larvae Meals in Juvenile Nile Tilapia Diets: Performance, Digestibility and Hematological Responses Under Streptococcus agalactiae Challenge

Abstract

Simple Summary Fish farming depends on feeds rich in protein, but traditional ingredients can be expensive and raise environmental concerns. Insects are being studied as a more sustainable alternative because they can provide high-quality nutrients while using fewer natural resources. In this study, we tested whether meals made from two insect species, the yellow mealworm and the black soldier fly, could be included in diets for juvenile Nile tilapia. Fish were fed these diets for 82 days, and we evaluated growth, nutrient use, blood health indicators, and survival after exposure to a bacterial infection that commonly affects tilapia farming. The insect-based diets did not reduce fish growth or overall body condition. Fat digestion remained high, while protein digestion varied depending on the insect source. Some blood cell proportions also changed, suggesting that the diets influenced aspects of the fish immune system. After bacterial challenge, fish fed the insect diets showed lower mortality values than the control group, although the differences were not statistically significant. Overall, the results support the use of these insect meals as promising sustainable ingredients for tilapia feeds.