Detrimental effects of metronidazole on the liver of freshwater common carp (Cyprinus carpio L.).

The widely used antibiotic metronidazole (MTZ) was investigated for its toxic effects on the liver of the common carp (Cyprinus carpio L.). The fish were exposed to 0.1, 0.5, and 2.5 mg/L MTZ in water for 30 days, and parameters that are indicative of liver damage and oxidative stress were measured. MTZ increased liver ethoxyresorufin-O-deethylase, malondialdehyde, and glutathione levels, and elevated the activities of superoxide dismutase, catalase, aspartate aminotransferase, and alanine aminotransferase. These parameters usually showed significant differences in the 0.5 and 2.5 mg/L MTZ groups compared to the control group (p < 0.05). These findings indicated that MTZ induced oxidative stress and caused liver damage in common carp, suggesting that measures should be taken to avoid contamination of surface waters with MTZ.