Insects are considered as one of the alternatives to substitute fishmeal in aquaculture diets and many studies have recently been performed to evaluate its suitability.

A team of Italian researchers studied the effects of substitution of fishmeal with insect meal from Hermetia illucens in the diet of rainbow trout (Oncorhynchus mykiss). Three diets with increasing levels of insect prepupae meal inclusion (10%, 20% and 30%) in partial substitution of fishmeal and a control diet without insect meal were tested in a 12-week feeding trial. The team evaluated fish growth performance and gut microbiota composition.

Researchers said that Actinobacteria, Firmicutes and Proteobacteria represented the dominant phyla in both experimental groups. Among them, the abundance of Actinobacteria and Proteobacteria was significantly influenced by including insect meal in the diet. Therefore, it is suggested that insect meal positively modifies fish gut microbiota, increasing its richness and diversity and in particular, increasing the amount of beneficial lactic acid-and butyrate-producing bacteria, that contribute to the global health of the fish. The study suggests that the prebiotic effect of insect meal is principally due to fermentable chitin.

Read study here.