Levels of Heavy Metal Cd, Cu and Zn in Three Fish Species Collected from the Northern Jordan Valley, Jordan

Cd, Cu and Zn concentrations were determined in muscle, bone, skin, scales and gills of three fish species (Oreochromis aureus, Cyprinus carpio and Clarias lazera) collected from northern Jordan Valley (Wadi El- Arab) during March, 2006. Heavy metal concentrations varied significantly depending on the type of the tissue and fish species. Generally, Oreochromis aureus showed the lowest levels of both Cd, and Cu metals in all tissues except gills. The other two fish species, Cyprinus carpio and Clarias lazera, showed less difference in their heavy metal levels but it was a significant difference (P 0.05). Cd and Cu recorded their lowest levels in muscle and their highest levels in gills. Cyprinus carpio fish species showed high values of Cu metal in all organs, except muscles. Oreochromis aureus accumulated the highest level of Zn in all organs particularly in their skin (432.11+ 152.14 mg/ kg dry wt.). Other studied fish species showed a high values of Zn in their skin, but not as high as that in Oreochromis aureus. The other two fish species showe dno significant difference in Zn level between all of their different organs. It was concluded that the level of heavy metals (Cd, Cu and Zn) in muscles of the three fish species were within acceptable limits by FAO standards, except for the Zn concentration in muscles of Oreochromis aureus (70.76+ 31.21 mg/ kg dry wt.) which might be due to the increase of agricultural influx and some other anthropogenic activity in that area.