Effect of short-term high temperature stress on plasma biochemical and hematological parameters in juvenile blunt snout bream, Megalobrama amblycephala

In this study, we investigated the effects of high temperature on plasma biochemical indicators and hematological parameters in blunt snout bream ( Megalobrama amblycephala ) following high-temperature stress. The fish (17.72 ±0.05 g) were exposed to two temperature conditions: a control group at ambient temperature (25°C, measured temperature 25.25 ± 0.34°C) and a high-temperature treatment group (34°C, measured temperature 33.07 ± 0.26°C). 6 fish were randomly sampled from each group at 0, 3, 6, 12, 24, and 48 hours. The results showed that high temperature significantly affects both plasma and hematological parameters. In the high-temperature group, both alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities initially increased and then decreased with prolonged stress duration. Alkaline phosphatase (ALP) activity reached its lowest point at 48 hours in this group(P < 0.05). Total protein (TP) and albumin (ALB) levels in the high-temperature group decreased significantly after 3 hours (P < 0.05). Glucose (Glu) levels in the high-temperature group increased significantly at 24 hours (P < 0.05). As stress duration increased, white blood cell count (WBC), red blood cell count (RBC), hemoglobin (HGB) levels, and hematocrit (HCT) in the high-temperature group all showed an upward trend. The results indicate that high-temperature stress induces pronounced stress responses, liver dysfunction, and adaptive alterations in blood oxygen-carrying capacity in blunt snout bream.