The fishes of the Euphrates and Tigris rivers are reviewed and 242 is the total species from 58 families are recognized. From these, and 126 are coastal species, many just entering the lower Shatt Al-Arab during salt water intrusion. Additional 107 species are anadromous (Tenualosa ilisha) or restricted to freshwaters including one species (Aphaniops stoliczkanus) found in freshwater, brackish water, and marine habitats. Three families (Cyprinidae: 30 species, Leuciscidae: 22 species, Nemacheilidae: 37 species) dominate the freshwater fish fauna. The largest genus is Oxynoemacheilus with 24 species in the area. Endemic to the Euphrates and Tigris are 87 species (77%) of freshwater species. Most non-endemic freshwater species occur also in the Iranian rivers of the Gulf, while six species are shared with the Mediterranean and one each with the Black Sea and the Caspian Sea basins.