ANXIETY ON THERMAL TOLERANCE AND SWIMMING ABILITY IN FEMALE ADULT ZEBRAFISH (DANIO RERIO)

To investigate the impact of anxiety on the thermal tolerance and swimming ability of fish, this study focuses on female adult zebrafish (Danio rerio), where experimental subjects were randomly divided into anxious and control groups. The anxious group underwent a 2-week treatment of chronic unpredictable stress (UCS) to establish an anxious model, while the control group remained untreated. Following the treatment period, anxiety-related behavioral indicators, whole-body cortisol and estradiol levels, thermal tolerance Critical thermal maximum (CT_max), critical thermal minimum (CT_min), lethal thermal maximum (LT_max), and lethal thermal minimum (LT_min), and swimming ability (Maximum sustained swimming speed, U_cat) were assessed in both groups. The results showed significantly heightened anxiety levels and cortisol concentrations in the anxious group compared to the control group (P<0.01), accompanied by notably lower estradiol levels (P<0.01). The CT_min of the anxiety group was significantly elevated in contrast to the control group (P<0.01), and LT_min also showed a higher trend (P<0.05), although no statistically significant differences were observed in CT_max, LT_max, and U_cat between the two groups (P>0.05). The study suggests that a 2-week UCS regimen effectively establishes an anxiety model in zebrafish, and the consequential reduction in estradiol secretion in adult female may detrimentally impact reproduction in the later stages. Additionally, anxiety attenuates the cold tolerance of zebrafish, which may be related to the elevation of cortisol levels and the decrease in physical fitness caused by anxiety.