Effects of black soldier fly meal and its components on the growth performance, nutrient reten-tion, gut histology and gut microbiome of rainbow trout

Insects, such as black soldier flies (BSF), have garnered attention in the aquacul-ture industry as a sustainable protein and lipid alternative to fishmeal and fish oil. However, research is lacking in understanding the beneficial effects of insect diets on fish growth and health. The aim of this thesis was to investigate the effects of feeding BSF and BSF components, such as oil and chitin, on growth performance, nutrient utilization, plasma biochemistry, gut histology and gut microbiome of ju-venile rainbow trout (Oncorhynchus mykiss). Two 12-week feeding trials were performed where rainbow trout were fed with fishmeal and soybean-based diets, respectively, where fishmeal and fish oil were replaced with 5 and 10% full-fat BSF, 5 and 10% defatted BSF, 4% BSF oil and 1% BSF chitin. Growth performance and nutrient retention were slightly better in fish fed the BSF oil and chitin sup-plemented diets, which also had changes in gut histology and the microbiome.