This study assessed the effects of oxygen and ozone nanobubbles on gill morphology, weight gain, and mortality of Pacific white shrimp (Penaeus vannamei), as well as the level of Vibrio parahaemolyticus and water quality of shrimp culture tanks under lab conditions. Two experiments were carried out with oxygen macrobubble, ozone macrobubble, oxygen nanobubble, ozone nanobubble, and control treatments (air-stone macrobubble). Experiments were done in triplicate in 100 L tanks with 15‰ saline water, and 20 shrimp per tank. Tanks in Experiment 1 were not inoculated with bacteria; tanks in Experiment 2 were inoculated with V. parahaemolyticus at a concentration of 10⁶ CFU/mL. The results revealed that short treatments with ozone nanobubbles had minimal impact on shrimp gills, mortality, and growth rates, reduced V. parahaemolyticus concentration in water compared to the other groups, and improve water quality

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High numbers of shrimp with mild to moderate gill damage were observed in the O3, and O2 (macrobubble) treatments but these lesions were much less common in the O2-NB and O3-NB (nanobubble) treatment groups in both experiments. These results suggest shrimp gills were most affected by the O2 and O3 treatments when these gases were not delivered using nanobubble form. The delivery of these gases using nanobubbles appeared to reduce the negative effect .f supersaturation. All treatments except the O3-NB treatment had a higher mortality at the end of the study than the negative control in the Experiment 2. Bacteria counts in water declined quickly in all tanks especially in the two O3 treatments suggested that besides increasing oxygen in the water, the use of O3-NB had the added benefit of reducing the bacterial load in the water and improved shrimp survival. Our study suggests that O3-NB can be applied to shrimp to effectively control V. parahaemolyticus, and hence, reduce AHPND. However, field studies are needed to confirm laboratory results and refine treatments for maximum effectiveness and use of O3-NB in intensive commercial shrimp farms.