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.

Puerarin, a bioactive isoflavone extracted from Pueraria lobata, possesses well-documented pharmacological properties, including anti-inflammatory, antioxidant, and metabolic regulatory effects, which have been extensively studied in mammalian models and traditional medicine. Recently, its potential as a functional feed additive in aquaculture has garnered increasing attention. This study aimed to evaluate the effects of dietary puerarin supplementation on growth performance, immune response, antioxidant capacity, and disease resistance in largemouth bass, Micropterus salmoides. A total of 120 fish were randomly assigned to 4 dietary groups, receiving a basal diet supplemented with 0 (control), 200, 500, and 1000 mg/kg puerarin for 8 weeks. The results showed that dietary puerarin significantly (p < 0.05) improved weight gain, with the 200 mg/kg and 500 mg/kg groups exhibiting the best performance. Puerarin supplementation enhanced acid phosphatase (ACP), alkaline phosphatase (AKP), and lysozyme (LZM) activities, reduced malondialdehyde (MDA) levels, and increased superoxide dismutase (SOD) and catalase (CAT) activities, indicating improved immune function and oxidative stress resistance in groups receiving medium concentrations of puerarin supplementation. The expression of the TNF-α, IL-6, IL-8, and HSP70 genes was significantly downregulated, especially in the 200 mg/kg and 500 mg/kg groups, suggesting anti-inflammatory and anti-stress effects, while Nrf2 expression was upregulated in the 1000 mg/kg group, reinforcing its antioxidative role. Additionally, puerarin-fed fish exhibited significantly lower mortality rates following Aeromonas hydrophila infection, highlighting enhanced disease resistance. In summary, the dose-dependent effect of puerarin on largemouth bass aquaculture has been revealed in this study. Dietary supplementation with moderate doses of puerarin (200 and 500 mg/kg) effectively suppressed inflammation and enhanced immune function, while the highest dose (1000 mg/kg) may mildly activate the immune system. These findings suggest that puerarin is a promising phytogenic feed additive for improving fish health and aquaculture sustainability.