What kind of fish is koi fish with four tails?

carp. Four-tailed koi fish is a special carp, which belongs to koi fish genus of Cyprinidae, and is a kind of artificially bred variety. Four-tailed koi fish is based on common carp, which was formed after a long period of selective breeding and reproduction. It is characterized by a large body, a dark blue back, a forked tail with four leaves, and a beautiful appearance, and is known as a "living work of art".