Monitoring trace metals in different tissues of Cyprinus carpio from the Indus River in Pakistan.

This replicated 4×2 factorial study investigated the bioaccumulation of selected metals (Mn, Pb, Zn, Hg and Cr) in four tissues (gills, liver, muscle and skin) of common carp (Cyprinus carpio) domiciled in two sites (upstream and downstream) of Indus River in Mianwali district of Pakistan. The data were statistically compared for the main effects of the site and fish organs and their interaction on the bioaccumulation pattern of these metals in fish organs at P<0.05. It appeared that the fish sampled from downstream had higher trace metals than the fish from upstream. Significant differences between fish organs were observed for these trace metals (P<0.001). The fish showed higher bioaccumulation of vital metals like Zn and lower bioaccumulation for the toxic metals like Pb. The gills had the highest metal load followed by liver, skin and muscles. High concentrations of Mn, Hg and Cr were observed in different fish organs as compared to the WHO and Federal Environmental Protection Agency standards for food fish. However, the mean concentration of Pb and Zn were under the permissible limits of food fish. It implies that higher levels of Mn, Hg and Cr in fish muscles would have detrimental effects on the health of fish consumers such as pregnant women, children and elderly people of this study area.