Amgun River (Russian: Амгу́нь) is a river in Khabarovsk Krai, Russia that flows northeast and joins the Amur River from the left near its mouth. The length of the river is 723 kilometres (449 mi). The area of its basin is 55,500 square kilometres (21,400 sq mi). The Amgun is formed by the confluence of the Ayakit and Suduk Rivers. Its main tributary is the Nimelen River. The Amgun teems with fish, such as Siberian salmon, humpback salmon, sturgeon, and carp. The Baikal Amur Mainline railway enters the Amgun River valley from the Dusse-Alin Tunnel and follows the river 180 kilometres (110 mi) northeast to Berezovyy where it turns southeast to Komsomolsk.