As a freshwater species, it can be found only in the catchments of rivers, ponds, and lakes located in China, Japan, the Korean Peninsula, Taiwan, the Russian Amur Basin and northen Vietnam.

[4] This species belongs to the family Siluridae and is characterized by a robust and elongated body that grows approximately 20 – 50 cm per year, which can reach lengths of up to 1.5 meters.

[5] S. asotus exhibits a distinctive appearance with a flattened, broad head and a terminal mouth, armed with numerous small, sharp teeth.

Its body is covered with smooth, scaleless skin, and its coloration can vary, ranging from olive-green to yellowish-brown, with irregular white dots along the side.

In juvenile fish measuring 6 to 7 cm (2.4 to 2.8 in) in standard length, this species exhibits an additional pair of mandibular barbels.

[6] S. asotus  is well-adapted to a variety of freshwater aquatic habitats, that range in temperature from 20 to 27 °C (68 to 81 °F), in Taiwan, China, Japan, and in all Korean rivers.

[7] It prefers an environment that is dense with grass with a free flow of water and light prevention due to sleeping habits.

This nocturnal feed is linked to poor floating ability due to bladder enlargement that only allows for swimming in freshwater's floors.

[11] In mountain village regions, Japanese catfish serve as a valuable protein source and are consumed as part of the local diet.

[12] Anglers pursuing this species often seek out freshwater habitats such as rivers and lakes in East Asia, including Japan, China, Korea, and Taiwan, where the catfish is prevalent.