The huchen (Hucho hucho) (, from German), also known as Danube salmon or redfish (), is a large species of freshwater fish in the salmon family of order Salmoniformes. It is the type species of its genus Hucho. Distribution and ecology The huchen is endemic to the Danube basin in Europe where the remaining population is threatened primarily by river damming, resulting in habitat fragmentation and loss through river impoundment and disruption of the longitudinal continuity of rivers, cutting away fish from its spawning grounds, with overfishing and fisheries mismanagement as an additional issue in many areas. Damming and all these other problems are especially visible in the Balkans. The upper reaches of the Danube basin, rivers and tributaries contain almost all of the recent population. This includes: In Austria: the Inn river, the upper Drava in Lower Austria, with the lower Gail in Carinthia, the Pielach, in Styria the upper Mur. In Germany: middle and lower Inn, Isar (especially in Munich) In the Balkans huchen still appears in following river systems: In Slovenia: in the headwaters of Sava and its tributaries. In Croatia: in the upper and middle course of Kupa. In Bosnia and Herzegovina: in the upper and middle Una, with the upper and middle Sana; the upper and middle Vrbas, with the lower and middle Vrbanja; the main channel of the Bosna lost its population due to degradation of its waters, its banks and riverbed, but its four main tributaries, the Krivaja, the Fojnička, the Lašva and the Željeznica, are still important habitats; one of the most important huchen habitats in the Balkans and Europe is the Drina, with its numerous tributaries, especially the Lim, the Tara and the Ćehotina, and smaller ones, the Bistrica, the Prača, and the Drinjača; In Serbia: the Lim. In Montenegro: the Lim, with the Lake Plav, the Ćehotina, and the Tara. Some of these habitats, especially in the Balkans, are endangered with planned, or already implemented plans for construction of new dams and hydroelectric power plants, such as on the Lim in Serbia, or like in case of the river Piva in Montenegro and Bosnia and Herzegovina, whose respective populations were completely wiped out since mid 20th century. In some cases rehabilitation of parts of the habitat is attempted, through restoration of the river course. Such positive example is the part of the course of the river Inn, with some -long