The Huchen or Danube Salmon (Hucho hucho) is a species of freshwater fish of the salmon family Salmonidae. It is native to the Palearctic ecozone. It occurs naturally in the Danube basin in Europe, however it has been introduced elsewhere on the continent. The Huchen is threatened with extinction. Efforts are being taken to reintroduce this species into the wild by commercially producing Huchen larvae. This is done by taking adults just before spawning and keeping them in special tanks. The fry are released once they are 1.5 to 4 inches.
This salmon has a slender body that is nearly round in cross-section. The back is reddish-brown and has several dark patches shown in an X or crescent pattern. Large adults are predatory and feed on other species of fish and other small vertebrates such as mice crossing rivers. The heaviest Huchen on record weighed just over 77 pounds and was just under 54 inches long. The Huchen is the largest freshwater fish in Japan.
These permanent freshwater fish spawn in April, once water temperatures reach 43 to 48 Â°F. The Huchen migrates up the river for spawning and the females excavate the gravel bed to make small depressions where the eggs are deposited. Larvae hatch in 30 to 35 days.