A comprehensive understanding of thermal tolerance in Percocypris pingi (Tchang, 1930) under different acclimation...

This study assessed the thermal limits of Percocypris pingi, initially reared at 9.86 °C. Fish were short-term acclimated to 12 °C, 18 °C, and 24 °C for two weeks, and their CT_max and CT_min were determined. A separate group underwent long-term acclimation in outdoor conditions, where water temperatures averaged 2.66 °C higher than the species' natural habitat. In September, when temperatures reached 28.91 °C, their CT_max was re-evaluated. Behavioral indicators-swimming speed, shoal cohesion, and temperature preference-were used to support thermal tolerance assessments. Our findings indicate that P. pingi exhibits a narrow thermal tolerance range. Specifically, fish acclimated at 12 °C, 18 °C, 24 °C and long-term acclimation of 28.91 °C showed CT_max values of 33.11 °C, 34.26 °C, 34.55 °C and 35.01 °C. Although CT_max increases only slightly with higher acclimation temperatures, recovery after the CT_max measurement was significantly impaired in the group acclimated at 24 °C for a short term. Only 13.33 % of individuals recovered within 30 min compared to 100 % in other groups. Behavioral analyses showed stable swimming speeds near CT_max in the 18 °C and 24 °C groups, but heightened activity in the 12 °C group. Additionally, shoaling behavior became more dispersed during CT_max testing. Temperature preference tests indicated a consistent inclination toward cooler zones (12-18 °C), suggesting that P. pingi may actively seek thermal refuges in natural environments to mitigate thermal stress. Habitat temperatures (19.5-27.6 °C) remain below the species' thermal tolerance (>33 °C), according to WorldClim data. Our temperature and behavioral data provide a reliable assessment of thermal risks for P. pingi and offer guidance for its conservation under climate change.