The Mongolian grayling (Thymallus brevirostris) is a freshwater species of fish of the genus Thymallus endemic to the landlocked rivers in Mongolia, Inner Mongolia Province of China and nearby parts of Russian far east.

It is considered to be the largest grayling species in the world,[2] and hence viewed as an auspicious sign by local tribes.

[3] Mongolian grayling grow to a recorded maximum length of 65 cm (26 inches).

[7] It is mostly found in the Central Asian basin of western Mongolia and the border region with Kazakhstan, as well as the Tuva Republic in southern Siberia.

[8] In autumn and winter, it forms large shoals in front of the estuaries in lakes before spawning.