For many years, aquaculture relied on the use of fish meal and oil as optimal ingredients, but presently they are no longer sustainable. Among several alternatives, the Black Soldier Fly (BSF) (Hermetia illucens ) represents a very promising candidate, even if its inclusion in aquafeed still faces some problems because of its unbalanced fatty acids profile and chitin content. At this regard, the enrichment of BSF growth substrate with a potential polyunsaturated fatty acid (PUFAs) source represents a valid method to improve the insect's nutritional value. In the present study, according to a circular economy concept, l and organic by-products (coffee silverskin ) added with a 10% (W/W) Schizochytrium sp was efficiently bio-converted in a highly nutritious insect biomass which, in turn, provided a sustainable new ingredient for fish culture. The present study investigated the effects of diets including increasing levels of BSF meal (0, 25, 50, 75, 100% with respect to fish meal) during a six-months feeding trial performed on zebrafish (Danio rerio ). Fish were sampled at 2 and 6 months and a multidisciplinary approach, including biometry, histology, gas chromatography, spectroscopy (FTIR), microbiota analyses and molecular biology was applied .
Results showed that insect's fatty acid profile can be improved by adding an adequate source of PUFAs in the growth substrate and that insect meal can be included in zebrafish diets up to 50% with respect to fish meal without significantly affecting fish physiology and development.
Higher inclusion levels negatively affected fish welfare and stress response
This study was funded by Ricerca Scientifica Cariverona, NUTRIFISH project N° 2017.0571