• digestive capacity;
  • Silurus meridionalis;
  • sit-and-wait forager;
  • specific dynamic action

The resting oxygen consumption inline image, postprandial and post-exercise peak oxygen consumption inline image of 137 juvenile southern catfish Silurus meridionalis, weighing 18·5 ± 0·8 g (mean ±s.d.), were measured at 25° C to determine whether inline image is positively related to postprandial and post-exercise inline image 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 inline image is positively related to growth rate. Postprandial inline image was positively correlated with inline image, while post-exercise inline image was not. Both postprandial inline image and post-exercise inline image were positively correlated with factorial and absolute scope. There was no significant correlation between the growth rate and postprandial inline image in S. meridionalis. It suggested that as a sit-and-wait forager with low inline image, low post-exercise inline image and high postprandial inline image, the expenditure of energy for maintenance in S. meridionalis may be more closely related to digestive processes than locomotor activities.