Seasonal variation in thermal tolerance, oxygen consumption, antioxidative enzymes and non-specific immune indices of Indian hill trout, Barilius bendelisis (Hamilton, 1807) from central Himalaya, India.

Abstract We studied the season dependent thermal tolerance, oxygen consumption, respiratory burst response and antioxidative enzyme activities in juveniles of Barilius bendelisis . The critical thermal maximum (CTmax), lethal thermal maximum (LTmax), critical thermal minimum (CTmin) and lethal thermal minimum (LTmin) were significantly different at five different seasons viz. winter (10.64 °C), spring (16.25 °C), summer (22.11 °C), rainy (20.87 °C) and autumn (17.77 °C). The highest CTmax was registered in summer (36.02 °C), and lowest CTmin was recorded during winter (2.77 °C). Water temperature, dissolved oxygen and pH were strongly related to CTmax, LTmax, CTmin and LTmin suggesting seasonal acclimatization of B. bendelisis . The thermal tolerance polygon area of the B. bendelisis juveniles within the range of seasonal temperature (10.64–22.11 °C) was calculated as 470.92 °C 2 . Oxygen consumption rate was significantly different ( p 2 /kg/h) and lowest in winter (32.60 mg O 2 /kg/h). Total white blood cell count including neutrophil and monocytes also showed significant difference ( p p 540 nm ) and minimum in winter season (0.054 OD 540 nm ). The activity of superoxide dismutase, catalase and glutathione-s-transferase both in liver and gill, also varied significantly ( p B. bendelisis , which modulate the thermal tolerance, oxygen consumption, respiratory burst activity and status of anti-oxidative potential in wild environment.