ENVIRONMENTAL FACTORS ON THERMAL TOLERANCE OF MIRROR CARP (CYPRINUS CARPIO VAR. SPECULARIS)

In order to investigate the effects of various factors on the thermal tolerance of cyprinid fish, specifically mirror carp (Cyprinus carpio var. specularis), which were utilized as experimental subjects to explore their critical thermal temperatures, including critical thermal minimum (CT_min) and maximum (CT_max), as well as lethal thermal minimum (LT_min) and maximum temperature (LT_max). Our study revealed that individual body size, exercise training, and starvation had no impact on the high temperature tolerance of mirror carp; however, these factors did affect the low temperature tolerance. Both CT_min and LT_min were lower in larger individuals compared to smaller ones (P<0.001), with a negative correlation between body weight and critical thermal minimum, indicating that larger body size enhances low temperature tolerance. The starvation group exhibited significantly higher CT_min and LT_min values than that of the control group (P<0.05), suggesting that starvation reduces the low temperature tolerance. Furthermore, food digestion had no effect on both high and low temperature tolerances in mirror carp. Although exercise training did not influence high temperature tolerance, it significantly improved low temperature tolerance (P<0.05). Overall, our findings demonstrate that while high-temperature tolerance in mirror carp is unaffected by body size, exercise training, starvation, or digestion, low-temperature tolerance is influenced by body size, exercise training, and nutritional status.