The purpose of this study was to evaluate the protective effects of vitamin C and chitosan on blood biochemical parameters in fish are exposed to paraquat. Fish were fed enriched diet with chitosan (1000 mg Kg^-1 feed), Vitamin C (1000 mg Kg^-1 feed) and vitamin C combined with chitosan and were simultaneously exposed to 0.02 mg L^-1 paraquat for 21 days. The results of this study showed that paraquat significantly increased aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP) activities, and significantly increased glucose, cholesterol, triglycerides, urea and creatinine levels as compared with control group (P< 0.05); However, paraquat decreased (P< 0.05) lactate dehydrogenase (LDH), acetylcholinesterase (AChE) activities and total protein and globulin levels. Compared with the control group, paraquat had not effect on plasma albumin levels (P> 0.05). Although administration of vitamin C or chitosan (alone) prevented changes in certain blood biochemical parameters in fish exposed to paraquat, the results showed that antioxidant properties of vitamin C are more than chitosan. However, administration of vitamin C and chitosan complex may prevent oxidative stress and inhibit changes in blood biochemical parameters in fish exposed to paraquat.