Soy oils as partial replacements for fish oil in practical diets for nile tilapia

Marine oil is a high-quality source of essential fatty acids, particularly n-3 long-chain polyunsaturated fatty acids (LC-PUFA) and therefore, the main dietary lipid source used in aquafeeds.  Unfortunately, high costs, safety, and environmental sustainability concerns regarding this commodity has forced the aquaculture industry to investigate alternative dietary lipid sources. In this study, ten ~1.0 g juvenile Nile tilapia were stocked in replicate tanks (n=4) and fed once daily to apparent satiation one of five diets containing fish oil or a 50:50 blend of fish oil and standard, highly saturated, low α-linoleic acid or hydrogenated soy-derived oil throughout a 12-week trial. Results showed no significant differences across all treatments for growth and feed conversion ratios. Fillet fatty acid profile mirrored dietary lipid source with higher concentrations of saturated, n-3, and LC-PUFA in fish fed the fish oil feed. Fillets from fish fed 50% soy-derived oils contained higher concentrations of monounsaturated, n-6, and medium chain polyunsaturated fatty acids. Replacement of fish oil with 50% soy-derived lipids allows for equivalent production performance in juvenile Nile tilapia. However, use of these lipids alters the fillet fatty acid profile.