This paper described hybrid between two species of Salmonidae Rainbow trout (Oncorhynchus mykiss) & Caspian salmon (Salmo trutta caspius). Caspian salmon is a native fish in the Caspian Sea which migrate for spawning to the Mazandaran Rivers in the northern part of Iran during the autumn. Annually some broodstock of this type of fish are caught from the rivers and carried to fish farm in order to produce smolts. Then released them to the rivers to preserve stock Rainbow trout is also used for intensive culture in Iran since we would like to have inherit intermediate of these species. After selection of broodstock and fertilization we assayed many factors such as: Feeding, growth, systematic, cytogenetic, internal organs, tolerance to deficiency of oxygen and high temperature. In addition, we also compared with control. The result showed that the hybrid is intermediate between parental and suitable for intensive culture.