noun
black carp; black koi
Refers to the wild-type common carp (Cyprinus carpio) with dark coloration, as opposed to ornamental koi varieties. Used in contexts of fishing, aquaculture, and biology.
この川では真鯉がよく釣れる。
Black carp are often caught in this river.
真鯉は錦鯉の原種とされている。
The black carp is considered the original species of the ornamental koi.
Compound of 真 (ma, 'true, pure') and 鯉 (koi, 'carp'), literally 'true carp', referring to the original wild form.