Effect of temperature on food consumption, immune system, antioxidant enzymes, and heat shock protein 70 of Channa punctata (Bloch, 1793).

The impact of water temperature on the physiology of Channa punctata (Bloch, 1793) was evaluated in the present study. Fish were acclimated at 25 ± 1 °C and then exposed at six different temperatures: 10, 15, 20, 25, 30, and 35 °C. C. punctata exposed at 10, 15, and 20 °C showed 30, 21, and 11% reduced food consumption, respectively compared to 25 °C. Significantly higher respiratory burst and myeloperoxidase activities were found in fish exposed at 20 and 25 °C after 12 h of exposure compared to other treatments. Nitric oxide synthase was significantly higher at 25 °C after 12 h and at 25 and 30 °C exposed fish after 7 days compared to others. The reduced glutathione level was significantly higher at 25 °C compared to other treatments after 7 days of exposure. The thiobarbituric acid reactive substances level was minimum at 25 °C. Significantly lower antioxidant enzymes, catalase, glutathione peroxidase, and glutathione S-transferase were found in gills of fish exposed at 25 °C compared to others in both samples. The highest antioxidant enzyme levels were found at 10 °C. Heat shock protein (Hsp) 70 levels were significantly lower in liver and muscle of fish exposed at 25 °C compared to other treatments. The Hsp level was significantly higher at 35 and 30 °C exposed fish compared to others after 12 h, and the level reduced after 7 days in these treatments. Thermal stress affects food consumption rate, immune system, antioxidant enzymes, and enzyme systems in fish. The elevated Hsp70 level serves as a biomarker of stress in C. punctata. Graphical Abstract.