Hilsa species are broadly described as largely anadromous fish with a large valuable population size. It is well-known as one of the most critical commercial and occurs in marine, estuarine and riverine environments Hilsa shad, Tenualosa ilisha locally known as Sbour, migrates to the freshwater environment of the Shatt Al-Arab River systems for breeding. It was determined the genetic variation in 70 specimens of T. ilisha from four sites at the Shatt Al-Arab River, the mtDNA cytochrome-b gene was selected as a molecular marker for detecting genetic diversity, origin, and divergence of the population through comparing them with 6 samples from different locations at Indo-Pacific. The AMOVA analysis showed that the variation between groups is 60.97% and 39.02% within population indicating statistically significant P value (P<0.05). Furthermore, the maximum likelihood phylogenetic tree showed two main clusters of all T. ilisha groups representing two stocks of separated breeding grounds have a common ancestor.

Keywords