The iwame trout or markless trout, Oncorhynchus masou var. iwame, is a fish in the Salmonidae family. It is endemic to Japan. Suspected to be not a real species since some time, it was recently confirmed as a particular morph occurring in some populations of the masu salmon or seema (Oncorhynchus masou). This morph is recessively inherited.

This morph occurs in the satsukimasu salmon (amago) and apparently also in the nominate subspecies yamame (Oncorhynchus masou masou), if these are not identical.

References

• Kottelat, M. 1996. Oncorhynchus iwame 2006 IUCN Red List of Threatened Species. Downloaded on 04 August 2007.