Trachinotus ovatus is one of the important species considered for deep-sea aquaculture due to its unique characteristics and significant contribution to marine fish aquaculture in China. Currently, deep-water net cage aquaculture of Trachinotus ovatus typically occurs in nearshore waters (＜20 m depth), often in bays or areas with island and reef cover, offering favorable aquaculture environmental conditions. However, transitioning to deep-sea aquaculture entails moving into deeper, more exposed waters where environmental factors such as flow velocity, wind, and waves can significantly impact fish farming and equipment. Fish are confined to specific aquaculture spaces and must constantly contend with tidal forces; excessive ocean currents can be detrimental, even leading to fish mortality. Therefore, understanding fish swimming ability and environmental adaptability is crucial when selecting species for deep-sea aquaculture. This study focused on Trachinotus ovatus, using a lane breathing apparatus to study its swimming ability under different flow velocities [at a temperature of (26.99±0.70) ℃]. Small [body length: (4.06±0.43) cm, weight: (2.61± 0.79) g] and large [body length: (11.06±0.70) cm, weight: (56.09±9.99) g] sizes of Trachinotus ovatus were selected for the experiment, and their swimming behavior, respiratory metabolism, and physiological and biochemical indicators were measured. The study aimed to understand Trachinotus ovatus' swimming ability, behavior, and exercise physiology, as well as to reveal its physiological and biochemical responses to changes in flow velocity, providing a technical reference for deep-sea net cage aquaculture of Trachinotus ovatus. The results showed that the induced velocities of small and large-sized Trachinotus ovatus were (3.90±0.64) and (0.96±0.13) BL/s, respectively. The critical swimming speeds were (91.83±10.97) and (99.78±12.66) cm/s, respectively, and the burst swimming speeds were about 112.20 and 114.25 cm/s. There was a significant linear positive correlation between tail wagging frequency and flow velocity. Under the same absolute flow velocity, the tail wagging frequency of small-sized Trachinotus ovatus was significantly higher than that of large-sized Trachinotus ovatus (P＜0.01). The static oxygen consumption rates were about (899±111) mg/(kg·h) and (525±95) mg/(kg·h) for small and large Trachinotus ovatus, respectively, higher than the exercise oxygen consumption rates of the 20%, 40%, and 60% U_crit flow rate groups. The exercise oxygen consumption rate and flow rate of both sizes of Trachinotus ovatus showed a power function increasing relationship. The minimum COT was observed in the 60% U_crit flow rate group. In summary, it is recommended to control the adaptive flow velocity for deep-water net cage aquaculture of Trachinotus ovatus to within 1.0 BL/s, with an aquaculture flow velocity not exceeding 100 cm/s, and the optimal flow velocity range of 54–60 cm/s. The sustained swimming abilities of several marine fish are as follows: Trachinotus ovatus ＞ Sciaenops ocellatus ＞ Acanthopagrus schlegeli ＞ Larimichthys crocea.