Fishmeal replacement with hermetia illucens meal in aquafeeds: effects on zebrafish growth performances, intestinal morphometry, and enzymology

Fishmeal (FM) is still the most important protein source in aquafeeds. However, due to the reduction of wild fish stocks used for FM production, its manufacturing it is now unsustainable. Insect meal represents a valid alternative to FM, due to the low carbon footprint of its production and its high nutritional value. The aim of this study was to investigate the potentials of replacing FM with black soldier fly (Hermetia illucens) meal (HIM) in aquafeeds, using zebrafish as the animal model. Four diets were formulated with increasing HIM/FM replacement rate (the control diet contained 20% FM). Mortality rates, growth performances, and feed consumptions were measured, and fish intestine samples were collected for histological and enzymatic analysis. After 49 days, all groups almost tripled their initial body weight (cumulative body weight gain ranged between 143.9 and 155.2 mg), and no statistically significant differences among treatments were observed in relation to growth performances and histological traits. Contrarily, trypsin, alkaline phosphatases, and alpha amylase–glucoamylase activities were significantly reduced when the FM replacement rate was increased. In conclusion, HIM may represent an alternative to FM, since no adverse effects were observed when it was included up to 20% in the zebrafish diet, even when replacing 100% of the FM.