In order to analyze the ecological adaptability of fishes in the Lishui River, the absolute and relative critical swimming speed ( U c r i t a , U c r i t r ) and the bursting swimming speed ( U b u r s t a , U b u r s t r ) were measured for Dongtingking crucian carp ( Carassius auratus var. Dongting ) (body length 9.61±1.63 cm, body weight 18.26±1.14 g) and Plagiognathops microlepis (body length 10.28±1.17 cm, body weight 22.14±4.06 g) in the Changde section of the middle reaches of the Lishui River in Hunan Province of China at a water temperature of (21.0±0.5) ℃. These data were obtained by a custom-built fish swimming ability measuring device in the laboratory. The study analyzed the relationship between behavioral indices and body length (BL), as well as the differences in these indices between the two species. The results showed that for Dongtingking crucian carp ( Carassius auratus var. Dongting ) U c r i t a was (25.65±2.71) cm/s or U c r i t r (2.72±0.28) BL/s, and U b u r s t a was (22.46±2.31) cm/s or U b u r s t r (2.35±0.12) BL/s. For Plagiognathops microlepis , U c r i t a was (34.09 ± 2.15) cm/s or U c r i t r (3.31 ± 0.23) BL/s, and U b u r s t a was (30.2 ± 3.14) cm/s or U b u r s t r (2.93 ± 0.42) BL/s. According to the results, the linear and nonlinear function models of the critical swimming speed, the bursting swimming speed and body length of different fish were obtained. There were significantly higher U b u r s t a and U c r i t a of Plagiognathops microlepis than those of Carassius auratus var. Dongting by the paired t-test (P < 0.05), with the same significant differences between
Song et al. (Sat,) studied this question.