Photograph courtesy Zeb Hogan
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The taimen is the world's largest salmonid. Once found over large areas of Russia, Mongolia, and China, the species is threatened by overfishing and habitat destruction.

Photograph courtesy Zeb Hogan


Hucho taimen, also known as the Siberian or Mongolian taimen, is the largest member of the salmonid family, which includes trout and salmon. It can grow six feet long, even bigger than the North American Chinook salmon. Though it is one of five taimen species in Asia, when people talk about “taimens,” they’re usually referring to this species.

These fish have gray-green heads with streamlined bodies that blend to reddish brown in the tail. While their bellies are nearly white, the fins are often dark red.

Diet and habitat

It is not just their size that makes this taimen a true river monster. They are ferocious predators that will explode out of the water to attack any mammals—rats, ducks, even bats—that may be unfortunate enough to end up in the water. Primarily, however, they eat different kinds of fish. They sometime chase their prey in packs, a practice that has earned them the nickname “river wolves.” They’re also known to turn on each other for a meal.

Taimens are potamodromous, which means that—unlike most other salmonids—they spend their entire lives in freshwater, usually in swift-flowing rivers with high oxygen levels. To spawn, the fish travel upstream to smaller tributaries and then drop back into the larger rivers.


These giants once swam in rivers from the Russian Pacific coast westward throughout the former Soviet Union and Mongolia. Today they’ve been wiped out from much of their range, and significant populations remain only in Russia and Mongolia.

The species has long enjoyed relative peace in Mongolia, where Buddhists revere it as the child of an ancient river spirit. Mongolia’s nomadic culture has traditionally eschewed fishing. But as lifestyles have shifted in modernizing Mongolia, logging, mining, and grazing have harmed water quality in the taimen’s range, threatening the fish there, too.

These giants are slow-growing. They take up to seven years to reach sexual maturity, which means populations can’t bounce back very quickly. Scientists say the removal of even a single large fish can hurt taimen populations. Although some people put the fish’s life span at 30 years, others claim that taimens can live for half a century or more.

Conservation efforts

Mongolia has been proactive in its conservation of the taimens, and recreational catch-and-release taimen fishing is now a significant revenue source for regional economies. Mongolian officials, along with several nonprofit organizations, are trying to find a balance to curb poaching yet promote regulated fishing and the revenue it brings. Enforcement of anti-poaching laws remains a challenge, however.