Hexavalent chromium induced hematological, antioxidant, neurotoxic and stress responses in starry flounder (Platichthys stellatus)

• The concentration of Cr 6+ in aquatic environments is increasing due to rapid industrialization. • Excessive accumulation of Cr 6+ can cause severe toxicity in aquatic organisms. • Waterborne Cr⁶⁺ exposure for 2 weeks reduced hematological parameters in P. stellatus . • Cr⁶⁺ exposure for 2 weeks increased plasma components, antioxidant responses, AChE and stress indicators in P. stellatus . • High concentrations of Cr⁶⁺ exposure may induce oxidative damage and neurological disruption in fish. Exposure to hexavalent chromium (Cr⁶⁺) in the aquatic environment can cause hematopoietic dysfunction in aquatic organisms and induce tissue damage, resulting in severe toxicity. Therefore, this study investigated the effects of waterborne Cr⁶⁺ exposure on the hematological parameters, antioxidant responses, neurotoxicity and stress responses of Platichthys stellatus and evaluated the toxic mechanisms of Cr⁶⁺. P. stellatus (mean weight 97.8 ± 16 g, mean total length 20 ± 0.8 cm) were exposed to waterborne Cr⁶⁺ at concentrations of 0, 2, 4, 8, 16 and 32 mg/L for 2 weeks. Hematological parameters (the red blood cell (RBCs) count, hemoglobin concentration and hematocrit value) were significantly decreased ( P < 0.05), whereas plasma components (calcium, glucose, cholesterol, aspartate aminotransferase (AST), alanine transaminase (ALT) and alkaline phosphatase (ALP)) ( P < 0.05) were significantly increased. In addition, antioxidant responses (SOD, CAT, GST and GSH) in the liver and gill tissues ( P < 0.05), acetylcholinesterase (AChE), heat shock protein 70 (HSP 70) and plasma cortisol were all significantly increased ( P < 0.05). Overall, these results indicate that waterborne Cr⁶⁺ exposure disrupts hematological and antioxidant response processes of P. stellatus and induces neurotoxicity and stress, suggesting that excessive accumulation of Cr⁶⁺ in aquatic ecosystems may pose potential risks to the health and aquaculture productivity of P. stellatus .