Trace elements incorporated into growing surface of the fish otoliths. It reflects the physical and chemical characteristics of the ambient water. Since otoliths grow continuously without re-absorption throughout the life of the fish, fish population growing up in different elemental composition. Trace element concentration in fish otoliths was analyzed by proton induced X-ray emission (PIXE). Otoliths were collected from Rutilus rutilus, during 1999-2000 in the eastern part of Caspian Sea. Ca, K, Sri Cu, Zn and Br in the otothis can be detected by using PIXE our results inform K, Sr, Fe, Zn as marker of this study. Therefore, in the two different conditions, separate 'age classes and without separate age classes, Astara and Turkmen regions were discriminated. Comparison of mean age in the different area show, deference of mean age is significant in the Astara and Turkmen. Iranian Fisheries Science Research Institute Published