Age determination is an important step in fisheries management. The cyprinid fish Chondrostoma regium (Heckel, 1843) is widely distributed in Tigris-Euphrates basin and the Mediterranean basins of southeastern Turkey and the northern Levant. In Iran, it is found in Karun and Karkheh Rivers, the Hoor-al-Azim Marsh and also in Zayandehrud River and Bushehr basin. This species is not found in other basins of Iran. However, there is little information about its habitat requirements. ... The aim of the present study was to investigate the length-weight relationship and age and growth of C. regium population in Bibi-Sayyedan River of Semirom, Isfahan as a tributary of Tigris basin in Iran
