The resting oxygen consumption , postprandial and post-exercise peak oxygen consumption of 137 juvenile southern catfish Silurus meridionalis, weighing 18·5 ± 0·8 g (mean ±s.d.), were measured at 25° C to determine whether is positively related to postprandial and post-exercise in sedentary S. meridionalis. In addition, postprandial metabolic response [i.e. the specific dynamic action (SDA)] after a satiating meal and the growth performance as a consequence of a 3 week feeding-growth trail were measured in 40 S. meridionalis, weighing 14·3 ± 0·2 g, at 25° C to determine whether postprandial is positively related to growth rate. Postprandial was positively correlated with , while post-exercise was not. Both postprandial and post-exercise were positively correlated with factorial and absolute scope. There was no significant correlation between the growth rate and postprandial in S. meridionalis. It suggested that as a sit-and-wait forager with low , low post-exercise and high postprandial , the expenditure of energy for maintenance in S. meridionalis may be more closely related to digestive processes than locomotor activities.