In the present study, the effects of dietary supplementation of low molecular weight sodium alginate on growth, body composition, anti-oxidant enzymes, digestive enzymes, and immune response in yellowfin sea bream juvenile (Acanthopagrus latus) were investigated. Fish (n=180) were divided into 3 groups with 3 replicates and received dietary treatments including basal diet without sodium alginate (control treatment), basal diet containing 5 g sodium alginate per kg diet (0.5% treatment), and 10 g sodium alginate per kg diet (1% treatment) for 8 weeks. The results showed that the final weight, weight gain, specific growth rate, condition factor, feed conversion, and protein efficiency ratios did not reveal a significant improvement compared to the control treatment (P>0.05). The obtained results indicated that dietary sodium alginate did not affect body composition (P>0.05). The activity of antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) in the groups fed on 0.5 and 1% sodium alginate showed a significant increase (P<0.05) compared to the control group. But, the activity of lipid peroxidation (MDA) in the groups fed on 0.5 and 1% sodium alginate showed a significant decrease (P<0.05) compared to the control group. The digestive enzymes increased significantly (P<0.05) by supplementation of sodium alginate, compared to the control group. Mucus lysozyme and complement activity were not significantly different (P>0.05). Overall, it can be concluded that feeding of yellowfin sea bream on the diet supplemented with 0.5 and 1 percent sodium alginate for a period of 8 weeks does not enhance the non-specific immune response and growth. Nonetheless, sodium alginate improved the activity of the antioxidant and digestive enzymes, indicating the positive effects of sodium alginate on enzymatic responses.
