Butterfly Koi, sometimes called Longfin Koi is a type of mutation that occurred in common carp which may or may not have relation to longfin carp of Indonesia. Due to their physical differences, Butterfly Koi are often disqualified from many official koi competitions and seldom bred in Japan; however, some Japanese breeders such as Suda and Yamazaki breed these longfin varieties to sell overseas where they have a stronger demand.
Quality patterns on butterfly koi are somewhat difficult to make as perhaps something in their genetics is causing them to recess back to more primitive forms. At least from what we have observed, the percentage of quality butterfly koi are much lower than their standard counterparts.
You can buy Butterfly Koi from Goldorado Aquatics here.