Rest metabolic rate(RMR) was measured using sealed respirometer and critical oxygen concentration(P_crit) was calculated using two-segmented straight lines method on Chinese Bream Parabramis pekinensis weighed 8.13 ± 0.15 g(n=31) at 15,20,25 and 30℃.The RMR was 132.22 ± 4.97,182.67 ± 12.49,218.44 ± 9.20 and 298.32 ± 9.96 mg O₂ /(h.kg) respectively at 15,20,25 and 30℃ with an ascending trend with temperature.There was a significant difference between groups(P < 0.05) except for the RMR at 20 and 25℃.The Q₁₀ value were less than 2 [1.91(15-20℃),1.43(20-25℃),1.87(25-30℃)]in all thegroups.The P_crit was 1.35 ± 0.09,1.16 ± 0.19,0.97 ± 0.12 and 0.86 ± 0.09 mg O₂ /L,S_crit was 13.87% ± 0.74%,13.32% ± 1.72%,12.15% ± 1.35% and 11.34% ± 0.65% at 15,20,25 and 30℃,respectively.The results revealed that P_crit decreased as temperature increasing while S_crit was relative stable with temperature change.Our study suggests that the conclusion of study on hypoxia tolerance capability in fish would be varied with different indices measured.It also indicated that in the process of fish physiological adaptation to hypoxia,the effect of relative oxygen saturation rather than the absolute oxygen concentration played determination role.Therefore,critical oxygen saturation index may be better practical in fish hypoxia tolerance study.