Abstract: The body composition and energy content in the wild Siniperca chuatsi and Channa argus of different sizes and in S.chuatsi and C.argus fed different rations were determined.For the wild S.chuatsi and C argus of different sizes, the contents of dry matter, protein, lipid and energy significantly increased with increasing body weight (P 0.05), ash content of the wild S.chuatsi also significantly increased with increasing body weight (P 0.05), but the regression relationship between ash content and body size in the C.argus was not significant (P 0.05).For S.chuatsi and C.argus fed different rahons, contents of dry matter, lipid and energy significantly increased with increased ration levels (P 0.05); the regression relationship between content of protein or ash and rahon level was not signiflcant in S.chuatsi (P 0.05); the protein content significantly increased with increasing rationleveI, but ash content significantly decreased with increasing ration level in C.argus (P O.O5).Though significant regression relahonship betWeen dry matter contentand contentS of protein, liPid and energy both in the wild S chuatsi and C.argus ofdifferent body sizes and in S. chuatsi and C. argus fed different rations were found (P 0.05), the regression equations established using the two sets of data did not agree completely.