Potential use of black soldier fly ( Hermetia illucens ) and mealworm ( Tenebrio molitor ) insectmeals in diets for rainbow trout ( Oncorhynchus mykiss )

Abstract

The aquaculture industry is diminishing the amount of fishmeal needed to maintain its protein demand. Alternatives are tested in this way, being insects one of the most promising. In this study, two different insectmeals were tested at different fishmeal replacement proportions (150 and 300 g·kg-1) in diets for Oncorhynchus mykiss. This study covers diverse aspects related to growth, protein utilization, physiological status of the fish, and quality of the final product. The inclusion of insectmeals had no negative effects on growth, protein utilization and on the physiological status of the fish. At the highest fishmeal replacement level with Tenebrio molitor, fish showed a higher digestibility of the protein, a reduction in viscerosomatic index and a higher aerobic catabolism, generating a pro-oxidative environment that was compensated by an increase in antioxidant enzymes, revealing the importance of choosing the appropriate insectmeal. A significant reduction in omega-3 fatty acids in the fillet was observed with an increasing insectmeal inclusion. The study proves that insectmeal can be a viable alternative for the partial replacement of fishmeal in rainbow trout, but further studies are needed to determine the most appropriate insectmeal, and to deal with the reduction of omega-3 fatty acids.