Channel catfish (Ictalurus punctatus) were subjected to 5 or 10 min of anoxia (removed from water) to rapidly increase blood lactic acid concentration metabolically. BloodpH decreased as blood lactic acid concentration increased. Respiratory rate increased in fish with lowered bloodpH and with increased blood lactic acid concentration during the 10 min after fish were returned to water after anoxia. Fish not treated had a mean bloodpH of 7.8. BloodpH decreased in catfish subjected to anoxia 5, 10, and 15 min and decreased further when the fish were returned to water. Lowered bloodpH was associated with loss of equilibrium and death in catfish subjected to transportation and handling.