''Gnathopogon caerulescens'', the Biwa moroko gudgeon is a species of

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fish or actinopterygians, is a class of bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built fins made of webbings of sk ...

in the genus ''

Gnathopogon ''Gnathopogon'' is a genus of freshwater Actinopterygii, ray-finned fish belonging to the Family (biology), family Gobionidae, the gudgeons. The fishes in this genus are found in eastern Asia. Species ''Gnathopogon'' has the following species. * ...

'' endemic to

Lake Biwa is the largest freshwater lake in Japan. It is located entirely within Shiga Prefecture (west-central Honshu), northeast of the former capital city of Kyoto. Lake Biwa is an ancient lake, over 4 million years old. It is estimated to be the 13 ...

in Japan. It is sometimes known by its Japanese name 'Honmoroko' (ホンモロコ).

References

caerulescens Freshwater fish of Japan Fish described in 1883 {{Gobioninae-stub