为探索水电梯级开发下鱼类的趋流行为，采用自制鱼类游泳能力及代谢测定装置，研究了3种沅水常见鱼类(鲫、大眼鳜和黄颡鱼幼鱼)的趋流游泳能力及代谢特征。结果显示，鲫、大眼鳜和黄颡鱼的相对感应流速分别为(0.79±0.14)、(1.16±0.07)和(0.75±0.09) BL/s，相对偏好游速分别为(2.31±0.11)、(1.86±0.04)和(1.60±0.03) BL/s，相对临界游速分别为(3.43±0.37)、(2.58±0.32)和(2.68±0.13) BL/s。同样条件下黄颡鱼偏好游速、临界游速、呼吸频率和耗氧率均显著低于鲫和大眼鳜。3种鱼呼吸频率、摆尾频率和耗氧率均随流速增加而增加，呈先升高后降低的趋势。在3.0 BL/s流速下，3种鱼呼吸频率均出现峰值。在2.0 BL/s流速下，鲫和大眼鳜摆尾频率和耗氧率出现峰值，而黄颡鱼则在1.5 BL/s流速下出现。随着流速的增加，鲫趋流率从静水组的64.1%增加至4.0 BL/s的100.0%，大眼鳜和黄颡鱼分别从静水组的60.2%和58.9%增加至2.0~3.0 BL/s的100.0%。水流流速显著影响3种鱼的游泳状态。鲫在静水条件下以逆流前进和顺流而下为主。大眼鳜静水和大多数流水条件下以逆流静止状态为主。黄颡鱼在静水组和较低流速组(<1.0 BL/s)长时间保持逆流静止状态，随着流速的增大，逆流静止比例迅速减少，逆流后退时间比例不断增加。研究表明，沅水3种常见鱼类趋流行为的差异性与其生活习性、形态特征、食性和捕食方式以及生活水环境等密切相关。了解3种鱼类趋流行为参数与流速环境条件的对应关系，有助于建立鱼类游泳生物学仿真数据模型，为梯级开发背景下鱼类的运动生理生态适应机制及运动方式的演化研究提供参考。
To understand the physiological and ecological adaptation mechanism of fish movement and the evolution of their movement mode from Yuanshui River, a branch of Dongting Lake water system, we investigated the swimming ability, rheotaxis behaviour and metabolic characteristics of local fish of different species and habits by the hydropower cascade development in this study. The rheotaxis behaviour and swimming metabolic characteristics of three familiar fish (Carassius auratus, Siniperca kneri, Pelteobagrus fulvidraco) from Yuanshui River were tested using a self-manufactured apparatus for measuring swimming ability and metabolism of fish by adjusting water velocity in the laboratory. The classical increasing velocity method and video counting method were used to study these data. The results showed that the relative induction velocities of C. auratus (15.84±3.60 g), S. knerii (27.10±7.41 g), and P. fulvidraco (17.50±4.78 g) were, respectively, (0.79±0.14) BL/s, (1.16±0.07) BL/s and (0.75±0.09) BL/s. The relative preferred swimming speed of the three fishes were, (2.31±0.11) BL/s, (1.86±0.04) BL/s and (1.60±0.03) BL/s, respectively, and the critical swimming speed were, (3.43±0.37) BL/s, (2.58±0.32) BL/s and (2.68±0.13) BL/s, respectively. Under the same conditions, the preferred swimming velocity, critical swimming speed, respiratory frequency (RF) and oxygen consumption rate (OCR) of P. fulvidraco were significantly lower than those of the two other fishes. At different flow rates, the RF, OCR and tail beat frequency (TBF) of the three species of fish all increased significantly with the increase of flow rate, and it showed a same tendency to first increase and then decrease. The RF of all fishes had peak values at the flow rate of 3.0 BL/s.The TBF and OCR values of C. auratus and S. kneri peaked at the flow rate of 2.0 BL/s, while that of P. fulvidraco was at the flow rate of 1.5 BL/s. The rheotaxis rate of C. auratus increased from 64.1% under the condition of still water to 100.0% at the flow rate of 4.0 BL/s, while S. kneri and P. fulvidraco increased respectively from 60.2% and 58.9% under the condition of still water to 100.0% at the flow rate of 2.0-3.0 BL/s. The swimming states of the three species of fish were obviously affected by the flow rate. Under the condition of still water, the swimming states of C. auratus were mainly in “moving forward against the current” and “downstream”. S. kneri under the condition of still water and most of the flowing water were at rest against the current. P. fulvidraco under the condition of still water and at lower flowing rate (<1.0 BL/s) were also mainly at rest against the current. With the increase of flow rate, the proportion of rest against the current decreased rapidly, and the proportion of “moving backward against the current ”increased continuously. Taken together, our findings indicated that the differences of the rheotaxis behaviour of three familiar fishes from Yuanshui River were closely related to their living habits, morphological characteristics, feeding habits, feeding patterns, and their living water environment.