Aspergillus niger-fermented watermelon rind enhances growth, immunity, and heat stress resilience in Asian seabass (Lates calcarifer)

< 0.05). Fish fed on 30 g FWRP/kg feed produced the highest values of growth, digestive enzymes, antioxidant, and immune indices. Activities of alkaline phosphatase and aspartate aminotransferase declined as levels of FWRP in diets increased, and their lowest levels were detected in fish fed on FWRP20 and FWRP30. The findings revealed that the use of fermented FWRP may serve as an effective feed additive for Asian seabass, promoting growth performance, enhancing antioxidant and immune responses, and increasing resistance to hyperthermia stress.