Alien fish species have negative effects on the abundance, diversity and richness of native fish species in southern Iraq. The numbers of alien fish species are constantly increasing due to the entry of invasive species. This has resulted in shifts in the historical composition of fish community structure and scarcity of some native species which represent the keystone in the building of fish populations.
Fish samples were monthly collected from three sites in southern Iraq (Al-Chibyaish marsh, the lower parts of Euphrates River, and the northern part of Shatt Al-Arab River) from April 2017 to June 2018. A total of 14,853 individuals of fish were sampled, which represented 26 species, 24 genera and 13 families of bony fishes. Ten alien fish species were recorded, affiliated to nine genera and five families, namely Cichlidae, Cyprinidae, Heteropneustidae, Poeciliidae and Xenocyprididae. Three alien fish species dominated the abundance in the three sites; the Prussian carp Carassuis gibelio comprised 12.58%, 26.19%, and 13.84%, the Blue tilapia Oreochromis aureus formed 16.78%, 13.66%, and 18.79%, , and the Redbelly tilapia Coptodon zillii comprised 7.37%, 7.71%, and 14.66% of the total number of species in three study sites respectively. ( …. )
These alien fish species created serious shifting in fish composition, diversity, richness, and abundance of native fish populations in comparison to the results of the historical survey in southern Iraq.
