Ichthyo-diversity in the Anzali Wetland and its related rivers in the southern Caspian Sea basin, Iran

The Anzali Wetland is one of the most important water bodies in Iran, due to the Caspian migratory fish spawning, located in the southern Caspian Sea basin, Iran. During a long-term monitoring program, between 1994 to 2019, identification and distribution of fish species were surveyed in five different locations inside the Anzali Wetland and eleven related rivers in its catchment area. In this study 72 fish species were recognized belonging to 19 orders, 21 families and 53 genera, including 66 species in the wetland and 53 species in the rivers. Among the 72 identified species, 34 species were resident in freshwater, 9 species were anadromous, 9 species live in estuarine and the others exist in different habitats. These species include 4 endemic species, 50 native species and 18 exotic species to Iranian waters. The number of species in different locations inside the Anzali Wetland was comparatively similar while it had high variation in different rivers. Twenty fish species are new records for the Anzali Wetland basin, including 10 estuarine, 5 ornamental, 2 riverine, one anadromous, one euryhaline and a small exotic fish.