Manoochehr Nasri - Department of Fisheries Science and Engineering, Faculty of Agriculture and Natural Resources, Lorestan University, Khorramabad.
Soheil Eagderi - Department of Fisheries, Faculty of Natural Resources, University of Tehran, Karaj, Iran

This study was conducted to evaluate the ILVKHVʼ composition of the Eivashan River, Lorestan Province. Here a total of 10 species were reported, including six native and four exotics. Those of the exotics includ Oncorhynchus mykiss, Cyprinus carpio,Pseudorasbora parva and Rhinogobius similis and native species were Garra rufa, Chondrostoma regium, Capoeta aculeata, Cyprinion macrostomum, Mastacembelus mastacembelus and Oxynoemacheilus frenatus. Exotic species are composed 33.3% of total ichthyofauna. Common carp and Rainbow trout had been introduced into the Eivashan dam for aquacultural porposes, however it seems that the two other exotics i.e. R. similis and P. parva were introduced unintentionally. Considering hight percentage of exotics, the fish biodiversity of the Eyvashan River is considered at risk and the destribution of these exotic fishes in the lower stream is alerted

Invasive fish, Natural fish population, Aquaculture, Fish cage culture, Biodiversity.