Impacts of substituting fish meal with full-fat or defatted black soldier fly (Hermetia illucens) larvae on growth, quality, and health of Nile tilapia (Oreochromis niloticus) fingerlings

This study investigated the use of black soldier fly ( Hermetia illucens ) larvae (BSFL), provided in either full-fat (FBSF) or defatted (DBSF) forms, as an alternative protein source in the diet of Nile tilapia ( Oreochromis niloticus ) fingerlings. Specifically, the influence was assessed of BSFL on growth performance, hematological parameters, body composition, and histology. Nine diets (including the control) were formulated to be isonitrogenous (35 % crude protein) and isolipidic (6 % crude lipid), relying on fish meal as the primary protein source and gradually replacing it with BSFL meal at levels of 25 %, 50 %, 75 %, or 100 % on an equivalent protein basis, corresponding to dietary inclusion levels of 5.25 %, 10.25 %, 15.5 %, and 20.0 %, respectively. Fish with an initial mean weight ± standard deviation of 1.3 ± 0.26 g were fed for 12 weeks until the fish final weight was in the range 24.08–34.95 g. Based on the results, there were no significant ( p >0.05) differences in the growth performance or feed conversion ratios among the treatments. Additionally, there were no significant differences in the hematological responses or the proximate body composition. Furthermore, 100 % substitution of fish meal with FSFL and DBSF meal caused blood congestion in the hepatopancreas region and several intraepithelial leukocytes in the intestine. There were no detrimental impacts at levels of 25 %, 50 %, and 75 % on growth performance, hematological responses, body composition, or the intestines or liver histological characteristics of the O. niloticus fingerlings. This information should provide useful guidance for the management of Nile tilapia, an economically important species. • Replacing fishmeal with FBSFL or DBSFL did not negatively impact growth, blood characteristics, or body composition in tilapia fingerlings. • FBSFL or DBSFL can replace up to 75 % of fish meal protein without negatively impacting intestinal and liver histology characteristics. • FBSFL or DBSFL are viable alternative protein sources for tilapia fingerlings diets.