What is "ricefish"

n. Any of the family Adrianichthyidae of about 27 species of small ray-finned fish, many of which are found in Japanese rice paddy.

The ricefishes are a family (Adrianichthyidae) of small ray-finned fish that are found in fresh and brackish waters from India to Japan and out into the Malay Archipelago, most notably Sulawesi. The common name of the group derives from the fact that some species are found in rice paddies. This family consists of about 32 species, some extremely rare and threatened, and some 2-4 may already be extinct.