Hermetia illucens meal from different substrates for replacing fishmeal: study on zebrafish as fish model

Black soldier fly ( Hermetia illucens ) has been extensively studied as effective bioconverter insect and its adaptability to different biowaste. The meal produced from the larvae is also one of the most promising candidate protein sources for replacing fishmeal in aquafeeds. The substrate nutritional composition is extremely important for an efficient insect growth, can modulate the nutritional value of the larval meal, and when included in aquafeeds it may affect fish growth and health. The effect of different rearing substrates on black soldier fly larval meal nutritional composition is not yet adequately investigated, so far. The purpose of this study was to investigate the effects of the use of black soldier fly larval meal obtained from strawberry by-product and spent grain for replacing fishmeal, on zebrafish growth parameters, gut health status, and reproductive performances. A total of 375 double transgenic zebrafish (Tg( coro1a:eGFP;lyz:Dsred )) were used to test five isoproteic, isolipidic and isoenergetic diets: a control diet including 35 % fishmeal, and four experimental diets including 25 % or 35 % of black soldier fly larval meal obtained from strawberry and spent grain, respectively (SB25, SB35, SG25 and SG35; 71 % or 100 % fish meal replacement rate, respectively). The results showed no negative effects on fish mortality, feed intake, and feed conversion rate, while fish fed both black soldier fly larval meal showed better growth parameters (final body weight, body weight gain, Specific Growth Rate and Condition factor) than control group. Among treatments, no differences were observed for macrophages and neutrophils density in the anterior gut portion, as well as on reproductive performances. Overall, the results of the present study suggest that H. illucens larval meal produced either on strawberry byproducts and spent grain, can be effectively used for replacing fishmeal in aquafeeds, with that enhancing aquaculture sustainability. • Effect of different Black soldier fly rearing substrates on meal and fish performance. • Black soldier fly meal for fishmeal replacement in aquafeeds. • Effect of Black soldier fly meal on fish growth performance, reproduction and innate immunity. • Black soldier fly meal for improving the circular economy and aquaculture sustainability.