Dietary selenium requirement and toxicity levels in juvenile Nile tilapia, Oreochromis niloticus

The importance of trace mineral, selenium (Se) supplementation in fish feed formulation has been well accepted since Se from ambient water and feed itself cannot supply the optimal level required by the cultured aquatic species. Even though, Se is typically required in much lower quantity in fish diet but its supplementation at optimum level is a critical issue in fish feed formulation. Scientific reports gathered over last two decades indicate, Se is quite sensitive and proper care should be taken to ensure their inclusion at optimum level in fish feed formulation. The present experiment clearly demonstrated that, freshwater fish juvenile Nile tilapia has a specific requirement level for dietary Se which cannot be met by regular feed and ambient water. Inclusion of dietary Se at optimum level is imperative to promote the maximum growth, tissue saturation and to ensure an optimum enzyme activity in Nile tilapia. Supplementing Se in fish feed beyond the requirement level may have toxic effects in freshwater aquaculture.