Hermetia illucens for Replacing Fishmeal in Aquafeeds: Effects on Fish Growth Performance, Intestinal Morphology, and Gene Expression in the Zebrafish (Danio rerio) Model

For improving aquafeed sustainability, insect meal is currently considered the most promising alternative to fishmeal. However, in this regard, more data are still necessary to avoid possible negative impacts on fish growth performance, metabolism, and welfare. The present study investigated the effects of increasing the inclusion of Hermetia illucens meal (0%, 17%, 33% and 50% of the feed, equating to 0%, 34%, 66% and 100% fishmeal replacement) on fish mortality, growth performance, intestine morphology, and gene expression of intestinal carriers. The results showed no adverse effects on fish mortality, feed intake and body weight and a positive effect on feed conversion ratio. Body weight gain was higher when 17% and 50% of Black soldier fly meals' feed included (34% and 100% fishmeal replacement, respectively). Gut morphology was not affected by the dietary treatments except for the area of PAS-positive goblet cells that was higher in the treatment fed 33% of insect meal. The mRNA expression of intestinal epithelium functionality-specific marker genes, such as slc15a1 (alias pept1, alias slc15a1b), gata4 and nfkb1b, confirmed that the insect meal-based diets might replace fishmeal-based diets without negative effects. Overall, the results of the present study suggest that using Hermetia illucens larvae meal as a replacement for fishmeal in aquafeeds might help to enhance sustainability while assuring favorable fish growth performance and gut health.