Effects of Sub-Lethal Toxicity of Paraquat on Blood Biochemical Parameters of Common Carp, Cyprinus carpio (Linnaeus, 1758)

Background: Paraquat is a non-selective contact herbicide, widely used to control weeds in agriculture farms and aquatic plants in surface waters. Paraquat can have adverse effects on the health of aquatic organisms. The aim of this study was to detect the alterations in the blood biochemical parameters of common carp exposed to sub-lethal concentrations of commercial formulations of paraquat. Methods: The fish were exposed to sub-lethal concentrations (0.2 and 0.4 mg.L-1) of paraquat for 21 days. Biochemical parameters including glucose, total protein, albumin, globulin, creatinine, triglyceride and cholesterol levels, and aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), creatine phosphokinase (CK), alkaline phosphatase (ALP) and γ-glutamyl transferase (GGT) activities were measured. Results: A significantly increase was observed in AST activity in fish exposed to 0.4 mg.L-1 paraquat. Paraquat caused a significant (P < 0.05) increase in plasma ALT, LDH and CPK activities and plasma creatinine levels. Although ALP activity significantly (P < 0.05) increased in fish exposed to 0.2 mg.L-1 paraquat, the fish exposed to 0.4mg.L-1 paraquat exhibited a significant (P < 0.05) decrease in ALP activity. A significant (P < 0.05) decrease in GGT activity, total protein, albumin and globulin levels as well as cholesterol and triglyceride levels was observed in fish exposed to sub-lethal concentrations of paraquat. Conclusion: Exposure to sub-lethal concentrations of paraquat may cause changes in blood biochemical parameters in common carp.