Oxidative stress, a critical factor affecting the health and productivity of aquatic organisms, arises from the imbalance between reactive oxygen species (ROS) production and antioxidant defenses. In aquaculture, natural antioxidants have gained increasing attention as sustainable feed additives to mitigate oxidative damage, enhance immune responses, and improve overall growth performance. This review provides a comprehensive synthesis of the antioxidative mechanisms of key natural antioxidants, including carotenoids, polysaccharides, vitamins, polyphenols, and flavonoids. By neutralizing ROS and modulating cellular signaling pathways such as Nrf2/ARE, these compounds offer significant protective effects against oxidative damage in aquatic species. The manuscript consolidates recent advancements in antioxidant research, highlighting their practical applications in feed formulation and their role in promoting sustainability in aquaculture. This review aims to provide an integrative framework for understanding natural antioxidants’ potential, guiding future research and practical implementation in aquaculture systems.

Oxidative stress (OS), defined as a disturbance in the balance between the production and elimination of reactive oxygen species (ROS), has been widely recognized as a key factor in the pathogenesis of various aquatic animal diseases. With the intensification of aquaculture and increasing environmental pressure, aquatic animals are frequently subjected to stressors that trigger oxidative stress, thereby compromising their health and productivity. This review comprehensively summarizes recent advances in understanding the involvement of oxidative stress in multiple organ-related diseases in farmed aquatic animals, including hepatic/pancreatic injuries, gill lesions, muscle degeneration, skin and shell disorders, metabolic disruptions, immunosuppression, and reproductive impairments. The underlying mechanisms involve excessive ROS-induced lipid peroxidation, inflammation, mitochondrial dysfunction, and the disruption of critical signaling pathways. Additionally, recent advances in nutritional antioxidants (e.g., vitamins, plant extracts), environmental regulation, and feed additives for mitigating oxidative damage are also discussed. A comprehensive understanding of the pathogenesis and regulation of oxidative stress is essential for improving aquatic animal health and enhancing the sustainability of aquaculture systems.