The Amur sculpin (Mesocottus haitej), also known as the Ussuri sculpin, is a species of freshwater ray-finned fish belonging to the family Cottidae, the typical sculpins. This species is found in eastern Asia where it is found in Russia, China and Mongolia - in the Amur River basin and some adjacent territories (the Tugur and the Uda Rivers flowing into the Sea of Okhotsk north from the Amur River, north-west of Sakhalin Island opposite the mouth of the Amur River). The Amur sculpin grows to a maximum published total length of . This species is the only known member of its genus, Mesocottus. According to the result of a pilot phylogenetic analysis, the freshwater Mesocottus is a sister lineage to the Cottus clade.[1]