Metal accumulation and antioxidant enzyme activity in C. gariepinus, catfish, and O. mossambicus, tilapia, collected from Lower Mguza and Wright Dams, Zimbabwe.

The aim of this study was to measure antioxidant enzyme activities as biological indicators of pollution in tissues of two species of fish. Five Clarius gariepinus and three Oreochromis mossambicus were collected from Umguza Dam (polluted dam) whilst seven C. gariepinus and eight O. mossambicus were collected from Wright Dam (relatively pristine dam). Diphosphotriphoshodiaphorase and catalase activities were consistently lower (42 +/- 2% and 78 +/- 20%, respectively) in liver whilst malondialdehyde levels were two times higher in muscles of both species of fish collected from Umguza Dam. However, seleniumdependent glutathione peroxidase (Se-GPX) activity was elevated four-fold in liver and gills of O. mossambicus collected from Umguza Dam. Metal levels were two to five times higher in muscles of both species of fish collected from Umguza Dam. Fish from Umguza Dam seem to have responded to pollution by increasing Se-GPX specificactivity in an effort to detoxify peroxides produced as a result of metal induced oxidative stress.