Abstract: To investigate the physiological mechanism underlying the maximum aerobic and anaerobic swimming ability and preferred swimming speed of fish in different habitats, we measured the critical swimming speed (U_crit), maximum constant accelerated swimming speed (U_cat), preferred swimming speed (U_pref), standard metabolic rate (SMR), maximum metabolic rate (MMR), and aerobic metabolic scope (MS) of the juvenile fish of five species at （25±1） ℃, including Spinibarbus sinensis, Carassius auratus gibelio, Procypris rabaudi, Mylopharyngodon piceusand Myxocryprinus asiaticus. Results showed that Spinibarbus sinensis showed the strongest swimming ability (both aerobic and anaerobic). Mylopharyngodon piceus and Myxocryprinus asiaticus were poor swimmers. The U_pref of all the five species fell into the range from 10 to 24.5 cm·s^-1, despite their significant variation in swimming ability. These results suggested that swimming ability of the selected fish species were mainly determined by cardiorespiratory capacity and morphology-induced swimming efficiency. Our results have certain reference value for designing fishways.

Key words: latitude, climatic factor, Metasequoia glyptostroboides, leaf trait, soil factor.