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In the closed basin of Central Asia, you can fish for the world’s largest grayling, a predatory cyprinid that reaches sizes of nearly 1 meter, all surrounded by some of the world’s most beautiful mountains, the Altai Mountains.

Our fishing trips in the Closed Basin of Central Asia:

Introduction to fly fishing in the closed basin of Central Asia.

Mongolia boasts three major drainage systems: the Arctic drainage, the Pacific Ocean or Amur River drainage, and the internal drainage of Central Asia. Understanding the history and evolution of each of these basins, as well as the location of the lakes or rivers where we will fish, is vitally important to know what species we will encounter.

One of Mongolia’s great assets is that, to date, there have been few translocations of species between basins or introductions of exotic species, an added value when fishing in a country as authentic in all aspects as Mongolia.

The closed basin of Central Asia, as its name suggests, is an endorheic basin, with only internal drainages not connected to oceans or inland seas. This basin includes the mountain lakes of the Mongolian Altai, the lakes of the Gobi Valley, and some lakes of the Hangayn Mountain Plateau.

In this basin, there are a total of 15 native species and three introduced species. It is a basin with low species diversity but, conversely, with a high degree of endemic species unique to Mongolia.

The low fish diversity of this basin and its isolation have helped some herbivorous species to develop behaviors of a great predator. It is important to note that in this part of the country, there are no pike or taimen.

Species of fish for fly fishing in the closed basin of Central Asia

The fish of interest for fly fishing in the closed basin of Central Asia are as follows:


This species of fish is known as the prehistoric fish of Mongolia. It is a member of the cyprinid family that inhabits some rivers and lakes of the Altai region such as Lake Khoton and Lake Khurgan, Uvs, Orog, Sangiin Dalai, and Lake Ust-Nur. It is an endemic species of Mongolia that is also found in some areas of southern Siberia.

Some of the main characteristics of the Altai Osman are as follows:

Longevity and Reproduction:

  • It can live for over 40 years.
  • It does not reproduce until it is 8-9 years old and reaches a length of over 20 cm.

Size and Weight:

  • It can reach lengths exceeding 90 cm.
  • Maximum weight of up to 15 kg.

Reproduction Season:

  • May – June.

Feeding Habits:

  • Young individuals are omnivorous.
  • Adults become carnivorous. This is a clear example of a species that, in the absence of predators, adults have adapted and evolved towards predatory behavior.

Preferred Habitat:

  • It prefers shallow lakes and rivers that connect lakes to each other.


The Mongolian Grayling, locally known as “khadran,” is one of the endemic species unique to a part of the closed basin of Central Asia. This grayling is considered the largest in the world, capable of reaching sizes exceeding 80 centimeters. This fish only inhabits the Altai Mountains, a UNESCO World Heritage Site located between Russia, China, Mongolia, and Kazakhstan.

One of the most characteristic features that differentiate this grayling from other species worldwide is its predatory behavior. With no natural predators, it occupies the top of the food chain in the rivers and lakes of the Altai Mountains. It is a highly aggressive fish with a unique predatory behavior compared to other species within its genus. This predatory behavior allows it to grow up to 20 centimeters larger than other graylings.

The best month to catch them is June when they migrate from the large lakes to spawn in the rivers. This moment is spectacular, and they can be caught using large dry flies, streamers, and nymphs, as they aggressively attack the bait.

The rivers and lakes of Mongolia where the Mongolian Grayling can be found include Khovd, Zavkhan, and Bogd rivers, as well as Khar, Khar Us, Achit, Tolbo, Airag, Tal, Khoton, Horgon, Dayan, and Huh lakes.


This subspecies of Arctic grayling, known as the Baikal Arctic grayling or in Mongolian as Shiwer khadran, inhabits rivers that flow into the Arctic Ocean. However, it is exceptionally found in the Khovd River, which belongs to the internal drainage basin of Central Asia. Without scientific knowledge and after analyzing much literature, we deduce that this species is located in this river because in the past there was some connection with the Arctic basin, another possibility is that it has been translocated. If anyone knows more about it and can inform us, we will be delighted to learn the reasons why it is found in this river.

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