Nutritional quality of rainbow trout fillets from fish fed with Hermetia illucens meal

In a world where the aquaculture sector is expected to provide more than the 65% of global fish demand by 2030 and the fish stocks are overexploited, the aqua-feed production based on alternative protein sources to the common fishmeal is necessary. Researchers are intensively looking at the use of insects as sustainable ingredient because of their fast growth, easy reproduction few nutritional requirements and their ability for recycling organic waste. Since no detrimental effects on fish growth and health emerged, Hermetia illucens meal has been accepted as protein source up to 25% for different fish species. However, such as substitution significantly modified fatty acid composition of fish fillets. The present research aimed at calculating the nutritional impact of the substitution of fishmeal at 0, 25 and 50% (C, Hi25, and Hi50 diets) with H. illucens in rainbow trout feed. Since the only recommendation about polyunsaturated fatty acid (PUFAs) intake in relation with their role for human health is the sum of eicosapentaenoic (EPA) + docosahexaenoic (DHA) acids per day, suggested in 500 mg, this amount was calculated in cooked fillets from rainbow trout fed diets including insect meal. Because of growing levels of H. illucens in aquafeeds, a significant reduction of EPA and DHA was observed, thus implying that consumers should increase the number of portions consumed every week in order to introduce the suggested 3.5 g of EPA + DHA per week. Specifically, people should eat around 196 g (= 2 scarce portions), 254 g (= 2.5 portions), and 311 g (= 3 portions) of trout fed with C, Hi25, and Hi50 diets, respectively. Such increase would imply an increase of the saturated fatty acids and the total caloric intake which could not properly be considered as healthy factors. Other aspects related to the sustainability of the fish meal replacement with alternative sources of protein should be properly considered.