The huchen, also known as Danube salmon or redfish, is a large species of freshwater fish in the family Salmonidae native to the Danube basin in Central and Eastern Europe. It is the type species of genus Hucho, being closely related to salmon, trout, char and lenoks.

Salmon is the common name for several commercially important species of euryhaline ray-finned fish from the genera Salmo and Oncorhynchus of the family Salmonidae, native to tributaries of the North Atlantic (Salmo) and North Pacific (Oncorhynchus) basins. Other closely related fish in the same family include trout, char, grayling, whitefish, lenok and taimen, all coldwater fish of the subarctic and cooler temperate regions with some sporadic endorheic populations in Central Asia.