abstract:Acrossocheilus paradoxus is a fast swimming fish, which is commonly found in the mid-stream of rivers in the western Taiwan. This study is to study some locomotive characteristics of performance of the fish, using a circular tank and high-speed camera system. The result shows that tail-beat frequency increases with swimming speed. However, no sighificant relationship was found between the tail-beat amplitude (0.16BL to 0.18BL), and swimming speeds. For a fixed swimming speed, the tail-beat frequency decreases as the body length increases. Since the body axis fluctuates moving from nose to tail, there is a phase difference when they moved. Also, the maximal amplitude of body axis occurs at the end of tail, and the minimal amplitude is at a quarter of body length starting from the tip of nose. The maximal speed is measured in a closed circular tank with controlled temperature, indicating that the maximal speed increases as temperatures are below 19°C. Conclusively, this may suggest that 19°C is the optimal temperature for sustained swimming.