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In this study, we investigated the seasonal changes in key eco-physiological traits of a wild population of snow trout, Schizothorax richardsonii from river Gola in the Indian Himalayan region over one year. Live specimens (5.8-3L4 g) were electro-fished from their natural habitat during representative months of four seasons with notable differences in water temperature, oxygen concentration and saturation. After 24-72 h of captive-acclimation, the fishes were examined for upper and lower critical thermal limits (CTmax, and CTmin), incipient lethal oxygen thresholds (ILOC and ILOS), apparent routine and maximum oxygen consumption rates (M-O2rout and M-O2max), and blood haemoglobin-haematocrit. Across the seasons, mean CTmin and CTmax values ranged from similar to 0 to 34.6 degrees C, suggesting a relatively wide acute thermal tolerance range for this predominantly cold-water fish. Changes in the habitat's thermal condition during winter to summer was reflected in the CTmin (similar to 0-2.4 degrees C) and CTmax (31.7-34.4 degrees C) estimates, while the highest thermal scope (CTmax-CTmin; 33.2 degrees C) was recorded in autumn. Concurrently, the incipient lethal hypoxia threshold observed in autumn (ILOS-2.6% and ILOC-0.19 mgO(2)/L) was significantly lower than the other three seasons, possibly linked to warm-acclimation. The reduction in blood haemoglobin-haematocrit levels during winter could limit the oxygen carrying capacity, with possible reciprocations in thermal tolerance and aerobic metabolism. Concerning body mass corrected oxygen consumption, the apparent M-O2rout was found to increase in a temperature-dependent manner from 150.3 mgO(2)/kg/h at 12 degrees C to 315.2 mgO(2)/kg/h at 26 degrees C, with Q(10) ranging from 1.6 to 2.2. Whereas, changes in M-O2max was not temperature sensitive (Q(10) of 0.7-1.3), except during spring-summer (Q(10)-2), with lowest and highest measurements in spring and autumn (934 and 1514 mgO(2)/kg/h), respectively. Collectively, these data form the first information report on the seasonal plasticity in thermal and respiratory physiology of a Schizothoracine fish species, bearing significance for their conservation, aquaculture and habitat monitoring.