Coldwater fishes are commercially valuable fish in all parts of the world. The grand total world production of Coldwater fishes in 2009 increased more than 2,172,517 t (FAO, 2011). Three species of cold water fishes are present in Iran’s water bodies but rainbow trout is the only one that is farmed commercially. The farming activity of this species has started with importing eyed eggs from USA since 1958 (Nafisi and Falahti, 2008). Imported eggs had been grown in a farm after karadj weir named Mahi saraye karadj and used as farmed fish and brood stock for the future. At present Rainbow trout fish is cultured in all provinces except Bushehr and Hormozgan. The provinces at the Alborz Mountain in North and Zagros Mountain in Northwest, west and southwest of the country are the largest producer regions (Nafisi, 2006).