Swimming performance is considered a critical character determining survival in many fishes in the natural circumstances.For many fishes,swimming is the main way to avoid the attack from their predators,obtain food,find a mate,and so on.Experimental tests are important means for measuring the swimming performance of fish.Many influence factors on fish’s swimming performance have been studied extensively.However,important as they are,no study has been carried out on the influence of acclimation time period, acclimation flow velocity and acceleration flow velocity on fish’s swimming performance.Experimental results measured under different acclimation conditions are incomparable and are always open to question.In this paper,the effects of acclimation flow velocity,acclimation time period,acceleration time period and testing flow velocity on the sustained swimming time of Sciaenops ocellatus and Acanthopagrus schlegel were studied.The Uniform Design method was used in the experiments where a 4-factor and 8-level design was applied to Sciaenops ocellatus tests and a 4-factor and 7-level design was applied to Acanthopagrus schlegel tests.The experimental results and theoretical analysis showed that the acceleration time period has greater effect on the sustained swimming time under stronger flow velocities than that under slower flow velocities.The influence of acceleration time period on the sustained swimming time is also related to fish species,fish size,current velocity,etc.It is suggested that the maximal acclimation velocity should be limited to 1.5 BL/s to avoid significant energy loss of testing fish.The acclimation time is recommended not to exceed 60 min though a longer time may be better for the fish to adjust itself to a new environment.A wellfitted powerfunction relationship was found between the sustained swimming time and the testing flow velocities.The sustained swimming time decreases significantly as the flow velocity increases.The conclusions obtained in this paper may give an important guidance to the testing approaches of fish’s swimming performance.