Malathion (S-(1, 2-dicarboethoxyethyl) O, O-dimethyl phosphorodithioate) is one of the organophosphate
pesticides comprehensively used in agriculture fields throughout the world. In spite of widely used, little information are available about DNA damage in aquatic organisms. Therefore, the present study carried out to investigation of DNA damage induced by malathion in Cyprinus carpio (Pisces: Cyprinidae) using single cell gel electrophoresis. The condition of experiment was determined in static system. The specimens were exposed to different non-lethal concentrations (0.5, 1.5 and 3 mgL-1) of the malathion for 96 hour (short-time exposed). Our results showed, the specimens exposed to different concentrations of malathion exhibited significantly higher DNA damage in their blood cells than the control sample (P<0.05). This study confirmed that the comet assay is useful method in determining genotoxicity of pesticides. Fish can be used for biomonitoring of the genotoxic pollutants in aquatic environment. Furthermore, DNA strand breakage can be used as biomarker in ecotoxicological studies.