Carassius cuvieri, the Japanese crucian carp or white crucian carp, is a species in the genus Carassius. It is found in Japan and, as an introduced species, in ******. This fish is closely related to the commonly known goldfish.

The original wild species unique to Lake Biwa is called gengorō-buna(ゲンゴロウブナ (源五郎鮒)), and is listed as an endangered species in the Japanese Red Data Book. There is a larger cultivated variant, with a taller body depth known as hera-buna(ヘラブナ) developed from the original species, cultured in the Osaka area and now released in many areas for sports fishing. It is enjoyed for catch-and-release, since it is not prized for eating.