Effect of incorporation of Spirulina platensis into fish diets, on growth performance and biochemical composition of Nile Tilapia, Oreochromis niloticus

The aquaculture industry is facing a growing need for a cost-effective, sustainable, and highly nutritious alternative to fish meal (FM) due to the increasing gap between supply and demand. This study investigated the effect of substituting (FM) with probiotics (Spirulina platensis) in fish feed on the survival, growth, and biochemical parameters of Oreochromis niloticus. Live tilapia fingerlings were stocked in 100-l glass aquaria. The feeding regimen consisted of four controls: commercial feed (C), formulated feed with FM (FMR₀), and formulated feeds with 25% and 50% replacement of FM (FMR₂₅, and FMR₅₀), respectively. The trial groups included FMR₂₅S₅ (25% FM replacement with 5% Spirulina), FMR₅₀S₅ (50% FM replacement with 5% Spirulina), FMR₂₅S₁₀ (25% FM replacement with 10% Spirulina), and FMR₅₀S₁₀ (50% FM replacement with 10% Spirulina). The trial period lasted for 24 weeks. Weight gain (WG) was most pronounced in FMR₅₀S₁₀ (p < 0.05). The SGR (specific growth rate) was highest for FMR₅₀S₁₀, FMR₅₀S₅, and FMR₅₀. A similar pattern was exhibited in the FMR₅₀S₁₀ group for length gain (LG). The protein efficiency ratio (PER) values were maximum in FMR₅₀, FMR₅₀S_5, and FMR₅₀S₁₀. FMR₂₅S₁₀, FMR₀, and FMR₂₅ exhibited the highest feed intake (FI) (p < 0.05). Trial diets supplemented with Spirulina enhanced the activities of SOD, CAT, and MPO. FMR₂₅S₁₀ exhibited the highest GPx activity and appreciable flesh quality. Collectively, S. platensis enhanced growth and feed utilization and modulated biochemical endpoints in feeds.