In order to investigate phenotypic abnormality in Khorram-rud River in Lorestan province in Iran, 1982 specimens including 13 species were caught. For this purpose, 8 sites were chosen on Khorram-rud River in Khorramabad city from 10 Km upstream to 10 km downstream of the city. Fish were caught using a cast net. Most of the sampled fish were returned to the river if there were no phenotypic abn...