Cardiac and respiratory responses of rainbow trout, bluegills and brown bullhead catfish during rapid hypoxia and recovery under normoxic conditions

1. 1. Heart rate, ventilation rate and routine oxygen consumption were measured in Salmo gairdneri, Lepomis macrochirus and Ictalurus nebulosus during rapid hypoxic stress and recovery under normoxic conditions. 2. 2. Cardiac and respiratory responses during hypoxia were similar to those reported in the literature for teleost fish. 3. 3. Immediate increases in heart rate and ventilation rate occurred in all three species after stress. When the mean heart rate for each species at 1 hr post-stress was compared with its pre-stress rate, differences in recovery patterns were found in all species. 4. 4. During recovery from hypoxia, rapid increases in oxygen consumption above pre-stress levels occurred in S. gairdneri and L. macrochirus. No significant differences between pre-stress and post-stress values were found in I. nebulosus.