* Japanese name: Itou
* Scientific name: Hucho perryi
* Description: A huge fish, a member of the salmon family, the Japanese huchen grows up to 1 meter long. Also known as the Sakhalin taimen, it is Japan's largest freshwater fish. Its size alone is distinctive enough (folk stories tell of huchens almost 2 meters long), but its powerful bulging jaw is another identifying feature. The huchen weighs 25-30 kg, has silver-gray skin and black spots, and when breeding acquires a red tinge.
* Where to find them:If you are lucky, in rivers in northern and eastern Hokkaido. Huchen used to also live in northern Honshu, but now are only found in Hokkaido, and even there are rare. They feed in the sea during the winter, and move into the rivers in the spring and summer to breed.
* Food:Young huchen feed mainly on aquatic insects. Older fish, larger than 30 cm, hunt and eat other fish. The really big ones may also eat mice, frogs and even snakes.
* Special features:As the snow melts in spring, sexually mature huchen move upstream. Males become mature at 6 or 7 years old, when they are about 45 cm long; females at age 8 , when they are 55 cm long. Unlike common salmon, huchen don't die once they've reproduced, and can survive for 15 to 20 years. This extraordinary lifespan is the reason they can get so big. For reproduction, females dig a rudimentary nest in the sand or gravel of the river bed, called a "redd." After she lays her eggs -- some 2,000-10,000 of them -- they are immediately fertilised by an accompanying male. The female then covers the eggs with gravel or sand. But despite the vast number of eggs, today there are few adults surviving. The hutchen is not only Japan's largest fish, it is one of the rarest, and its most venerable. It is thought that huchen have swum here for at least 2 million years. Biologists are now studying how much genetic diversity is left in the relatively few individuals that remain, and thus how much hope there is for the future survival of the species.
PHOTO COURTESY OF BIO-IMAGE NET