Study On Resting Metabolic Rate In Bagrid Catfish (Mystus Macropterus Bleeker)

From March, 2001 to January, 2002 the resting metabolic rates for 114 fish of Mystus macropterus, which were collected from Jialing River with weight ranging from 13.0g to 400.4g, were measured by a closed respirometer at the temperatures of 12.5, 17.5, 22.5 ,27.5 and 32.5, respectively.The results were as follows:(1) There was no difference the specific metabolic rates between the female and the male at each of the same temperature. Standard-weight metabolic rate in the female of IV gonad phase was slightly higher than those in the female of II and III gonad phase at 27.5, but the statistical analysis indicated that the difference was not significant. The result suggested that the effect of sex and the gonad developmental condition on the resting metabolism was no significant.(2) The specific weight metabolic rates increased with temperature increasing. There was double-logarithmic linear correlation significantly between specific weight metabolic rate and temperature in each of weight groups. Temperature exponent (B) in the regression equation increased with weight increasing. The covariance analysis showed that the difference between the every two temperature exponents in the equations was significant.(3) Specific metabolic rates decreased with weight increasing. There was double -logarithmic linear correlation between metabolic rate and weight at each of tested temperatures. The covariance analysis indicated that the difference was significant between the intercepts in the regression equations, but not between the slopes.(4) Regression analysis showed that interaction of weight (W: kg) and temperature (T:) on the resting metabolic rate (Ms: mg (O2/kg/h) was not significant. The correlation was developed as Ms= 1.320 T0.334) W0.184).(5) Based on the models reported the standard - weight metabolic rates of S. meridionalis and S. asotus were estimated. The metabolic rate in M. macropterus was 1.82 and 1.49 times of those in S. meridionalis and S. asotus, respectively.The discussions suggested:(1) Due to the effect of body weight on the metabolism might be brought into antagonism with that of developmental condition of the gonad, the difference between the metabolic rates in the tested fish at the different condition was insignificant.(2) The metabolic rate in M. macropterus was higher than that in either S. meridionalis or S. asotus could be understood on the different ecological habits among them. For example, the level of spontaneous activity in M. macropterus was higher. And the level of routine activity of the tested fish in large-scale closed respirometer in this study was higher than those of the either, which was restricted by the smaller room of respiratory chamber in the continuous-flow respirometer used in the two reported studies..