Black soldier fly oil-based diets enriched in lauric acid enhance growth, hematological indices, and fatty acid profiles of Nile tilapia, Oreochromis niloticus fry

A 90-day trial was conducted to investigate the effect of a diet containing Black Soldier Fly Oil (BSFO) on performance, feed efficiency, hematological indices, and fatty acid profiles of Nile tilapia, Oreochromis niloticus fry. BSFO, which naturally contains lauric acid (LA, 12:0), was utilized to create five isonitrogenous (300 g kg−1 CP), isolipidic (62 g kg−1 EE), and isocaloric (19.27 MJ kg−1 GE) experimental diets. The basal experimental diet (control diet, SBO100) had no BSFO added. Diets 2–5 were formulated by substituting soybean oil (SBO) with BSFO at 25 % (SBO75-BSFO25), 50 % (SBO50-BSFO50), 75 % (SBO25-BSFO75), and 100 % (BSFO100), resulting in LA content of 0, 0.4, 0.81, 1.21 and 1.61 mg g−1 fatty acid (FA), respectively. A total of 375 fish, weighing an average of 0.16 g, were stocked at a stocking density of 25 fish tank−1 the fish were separated into five treatments in triplicate and the experiment lasted 90 days. Diets supplemented with BSFO had a significant (P ≤ 0.05) influence on performance inducers and FCR. The fish fed with SBO75-BSFO25 had the highest performance parameters and best FCR values as compared to other treatments, but these values decreased when BSFO was added to more than 25 % of the diet. Total body FA contents increased as dietary BSFO levels increased. The opposite pattern was observed with n-6 PUFAs, n-3 PUFAs, and n-3/n-6 ratios. Fish-fed SBO75-BSFO25 exhibited the lowest levels of ΣSFAs, ΣMUFAs, Σn-3 PUFAs, and Σn-6 PUFAs compared to other treatments. Increasing dietary BSFO levels resulted in higher FA productive value (FAPV) for ΣMUFAs, Σn-3 PUFAs, and Σn-6 PUFAs. The opposite pattern was observed for ΣSFA values compared to fish fed with SBO75-BSFO25. All hematological indicators were within normal levels for healthy tilapia, indicating that BSFO had little or no impact on their health. The current study concluded that BSFO can substitute soybean oil (SBO) by up to 25 %. LA is especially beneficial, for improving growth performance, feed utilization efficiency, fatty acid profile, and hematological homeostasis in Nile tilapia, O. niloticus fry.