The Butterfly Fin Koi is reported to be more hardy than the standard fin. This is based on genetics with what is called hybrid vigor (heterosis). The Butterfly and Standard fin will inter-breed easily. The Butterfly have beautiful pectoral, ventral, dorsal, and caudal fins that are long, flowing and almost featherlike in appearance.
They are truly the most beautiful Koi because of their fins. They come in exactly the same colors, scale patterns, and metallics as standard fin Koi, and have the same names.
They are truly what the Chinese describe as "swimming flowers", and the Japanese as "living jewels".
The Butterfly Koi breeding program originated in the United States in the early 1980's. At that time, Wyatt Lefever obtained some unusual long-finned hybrid Asian carp. He started a breeding program crossing them with metallic colored Koi resulting in "Butterfly Koi".
Butterfly (long-finned) Koi are not only beautiful with long flowing fins, but they are quite hardy and able to withstand colder temperatures better than many traditional Koi.