Oxidative stress and immune responses in whiteleg shrimp (Penaeus vannamei) under ozone nanobubbles exposure

Ozone nanobubbles (NB-O₃) have recently emerged as a promising technology in aquaculture for improving water quality and disease control. However, their impacts on shrimp remain poorly understood, particularly regarding their effects on biochemical processes. This study evaluated the effects of NB-O₃ on growth performance, immune responses, oxidative stress, and HSP70 gene expression in whiteleg shrimp (Penaeus vannamei). Shrimp were cultured for 21 days in control and NB-O₃-treated tanks. Growth indices, water quality variables, total hemocyte counts (THC), antioxidant enzyme activities (catalase (CAT), glutathione peroxidase (GPx)), malondialdehyde (MDA), and HSP70 expression in hepatopancreas were assessed. Results showed that NB-O₃ significantly improved final body weight, weight gain, and average daily growth rate compared with the control (p < 0.05). Water quality was enhanced in NB-O₃ tanks, with the reduction of NH₃-N, NO₂-N, COD, and Vibrio counts. THC increased markedly in the NB-O₃ group during the early experimental phase. Antioxidant enzyme activities (CAT and GPx) were significantly elevated under NB-O₃ treatment, while MDA levels were lower at the end of the trial, indicating reduced oxidative damage. HSP70 expression in hepatopancreas peaked at day 1 in the NB-O₃ group, suggesting an instantaneous stress response, but declined thereafter, reflecting shrimp adaptation. These findings demonstrate that NB-O₃ improves water quality, enhances antioxidant and immune responses, and promotes growth in P. vannamei, supporting its potential application as a sustainable aquaculture technology. Overall, this study highlights NB-O₃ as an eco-friendly approach to enhance shrimp health and productivity in intensive culture systems.