Responses of crucian carp Carassius auratus to long-term exposure to nitrite and low dissolved oxygen levels

► Under low dissolved oxygen conditions there was a decrease in growth and feeding. ► Red blood cell count increased significantly with decreasing dissolved oxygen. ► There was a significant interaction between dissolved oxygen and nitrite on RBC. ► Hemoglobin content increased significantly with decreasing dissolved oxygen. ► Oxidative stress occurred under low dissolved oxygen and high nitrite.