Effect of Water Temperature on the Physiological Responses of Asian Catfish Clarias batrachus (Linnaeus 1758)

Temperature plays significant roles in the life of poikilothermic aquatic animal fish. The physiological responses of Clarias batrachus (Linnaeus 1758), magur (80.60±5.34 g) at different temperatures were observed. Fish were acclimated at 25 °C for 21 days and were exposed at 10, 15, 20, 25, 30 and 35 °C temperatures. Blood and muscle samples were analysed after 12 h and 7 days of reaching the assigned temperatures. Significantly (P 0.05) higher mortality of fish was found in 10 °C treatment compared to the other groups. At 10 °C, 50% fish died within 5 days. Serum protein was significantly (P 0.05) higher in fish exposed at 15 °C compared to the other treatments. Myeloperoxidase and reduced glutathione were significantly (P 0.05) higher in fish exposed at 30 °C and 25 °C, respectively compared to the other groups. Nitric oxide synthase was significantly (P 0.05) higher in fish maintained at 25 °C and 30 °C compared to the other treatments after 12 h and 7 days of exposure, respectively. Thiobarbituric acid reactive substance was significantly (P 0.05) higher in fish exposed at 10 and 15 °C compared to others after 12 h and 7 days of exposure, respectively. Lowering of temperature adversely affected physiological processes of magur.