Impact of Dietary Supplements on Growth, Immunity, and Feed Efficiency in Aquaculture Fish

A 56-day feeding trial was conducted to evaluate the effects of dietary prebiotics, probiotics, and synbiotic on growth, feed utilization, immunity, antioxidant capacity, and disease resistance in Nile tilapia (Oreochromis niloticus). A total of 240 fish (initial weight ~20 g) were randomly allocated into four dietary groups: control, prebiotic-supplemented (10 g kg⁻¹), probiotic-supplemented (Bacillus spp., 1×10⁸ CFU g⁻¹), and synbiotic-supplemented diets, each in triplicate. Probiotic-fed fish achieved the highest specific growth rate (SGR: 2.15 ± 0.04% day⁻¹) and lowest feed conversion ratio (FCR: 1.21 ± 0.03), followed by synbiotics (SGR: 2.07 ± 0.03; FCR: 1.26 ± 0.02) and prebiotics (SGR: 2.01 ± 0.05; FCR: 1.29 ± 0.04), all significantly better (p < 0.05) than control (SGR: 1.85 ± 0.06; FCR: 1.38 ± 0.05). Immunological parameters improved markedly, with lysozyme activity highest in probiotics (34.6 ± 1.2 U mL⁻¹) and SOD activity following the trend: prebiotics (28.4 ± 0.9 U mL⁻¹) > probiotics (27.1 ± 1.1) > synbiotics (25.8 ± 1.0) > control (21.7 ± 1.3). In the Aeromonas hydrophila challenge, survival rates were 88.9%, 91.7%, and 87.5% for prebiotics, probiotics, and synbiotics, respectively, compared to 66.7% in control, with corresponding relative percent survival (RPS) of 66.6%, 75.0%, and 62.5%. These findings demonstrate that dietary supplementation with probiotics, prebiotics, and synbiotics significantly enhances growth performance, feed efficiency, immune responses, and disease resistance in Nile tilapia, supporting their application for sustainable aquaculture.