Butterfly Koi

Butterfly Koi originated in the mid 20th century as a result of an effort to increase the hardiness of traditional koi. Japanese breeders interbred wild Indonesian Longfin river carp with traditional koi. The resulting fish had longer fins, long barbells, pompom nostrils, and were hardier than koi. These were known in Japan as "onagaoi" or "hire naga koi", or translated in English "long tail koi". Butterfly koi are strongly disliked by many keepers of traditional koi who view the breed as inferior to koi. This polarization of traditional keepers may be the reason why some koi retailers do not sell butterfly koi, and why many of Japan’s famous and most prestigious breeders do not breed butterfly koi today. They are largely unpopular in Europe and Asia, but are popular in the United States where they are more readily available. The popularity of these fish in the United States has earned them the nickname American Koi.`