Koi Varieties – Butterfly Koi

Welcome to our newest blog in the ‘Koi Varieties’ series where today we will be looking at Butterfly koi. Often referred to as Longfin koi or, in Japan, Hirenaga (hee-REH-nah-GAH) koi, these fish are a little different to other varieties of koi as the term refers to a body shape, specifically in the fins and tail, of a koi rather than a specific colour and/or pattern.


Butterfly Platinum Ogon koi (Nisai) from breeder Yamazaki

The name ‘Butterfly Koi’ has its origins in Indonesia and America and since the variety originated outside of Japan, many koi keepers think of the variety as ‘mutts’ or ‘impure’ koi, and others don’t even consider them to be koi fish at all! Others still, however, think that they are beautiful and graceful and can be the finest koi in their collection. As the name suggests, Butterfly koi have long, flowy, fins and a lovely, long graceful tail. This body type gives the fish a beautiful shape as it travels through the water often compared to a ballerina, or indeed, a butterfly!


Any koi variety can have the long, graceful fins associated with a Butterfly koi, although not all varieties have been specifically bred to have the long fins and tail associated with the Butterfly koi. When a koi has this fin-type, the variety name is preceded by the word ‘Butterfly’. For example, you could have a Butterfly Kohaku, Butterfly Benigoi, or Butterfly Goshiki. You could even have a koi that combines the butterfly with a scale type like Gin Rin and have Gin Rin Butterfly varieties!



History of Butterfly Koi


The Butterfly koi variety began in Indonesia in the early 1980s when a small population of carp fish, made up of common, brown and grey carp species, was discovered with long, flowing fins. No one knew exactly where these fish came from or how and why they came to have such long fins, but they were so interesting and different that news quickly spread, and they were soon imported to retailers around the world. One such company was based in New York, USA and imported these long-finned carp in the hope of them being popular with their American customers.


Gin Rin Butterfly Hi Utsuri koi (Nisai) from breeder Yamazaki

Unfortunately, the New York company had little to no success with their long-finned carp as the fish were considered ugly and undesirable. However, they did catch the eye of Blue Ridge Fish Hatchery, which, at the time, was America’s leading producer of koi and goldfish. When they saw an advert for long-finned koi, they were very intrigued and quickly placed an order. Unfortunately, when the fish arrived, the owner of Blue Ridge, Wyatt LeFever, was very disappointed to find that these fish were not koi carp at all and were instead just some plain, ugly wild carp. While he was disappointed, LeFever was reluctant to write these fish off altogether, so he gave them their own pond and some time to grow and develop.


That turned out to be a fantastic decision! Within a couple of years, the population in LeFever’s pond had significantly fallen but the fish that were left had developed beautiful, long, and flowy fins. Unfortunately, they were all still quite ugly in their colouration, but the development of their fins prompted LeFever to attempt to cross-breed the long-finned carp with some of his other koi carp, starting with some Gin Rin Yamabuki Ogon koi (yellow, single coloured, metallic koi with glittery, sparkling scales).


While there were some fears initially as the crossbred fry had the same appearance as the long-finned wild carp with none of the beautiful colours of the Yamabuki Ogon koi, success did eventually appear! As the fry grew larger, a small percentage of the group started to develop the beautiful golden colour of the metallic Yamabuki Ogon. As they continued to grow, the colour only got better! By the time the fish were a few years old, the small group of long-finned Yamabuki Ogon had developed into beautiful, angelic koi and had become the first longfin koi.



Butterfly Kohaku koi (Nisai) from breeder Yamazaki

For the first few years, in the late 1980s, the fish were marketed as longfin koi. When looking at some of his new koi, LeFever brought his young son, Randy LeFever (who later went on to take over the company) to have a look at the fish. Once he got to see the exciting new fish, Randy quickly exclaimed “Dad, they look like butterflies!”. And thus, the name stuck! Butterfly koi are now known all over the world with many different breeders developing different butterfly varieties. Even some breeders in Japan, like Yamazaki and Suda, have been producing fantastic Butterfly koi over the last 20-30 years.


Unfortunately, however, since Butterfly koi were developed only recently and outside of Japan, they have yet to be accepted at Japanese koi shows. In fact, it is likely that this decision from the Japanese koi shows is the reason that many people consider Butterfly koi to be ‘mutts’ or not ‘proper koi’. That being said, Butterfly koi are still incredibly popular with many koi keepers and breeders and have had great success in koi shows in countries other than Japan, especially in the US! They are always in high demand and add a touch of elegance to any pond. Butterfly koi are of particular interest to koi keepers with windows in their ponds as the variety is very beautiful when viewed from a side angle, as you can see in the below video, which is quite unique for a koi as most varieties are bred and developed to have the best pattern when viewed from above.



So, what should you look for when picking a Butterfly koi?


The most important thing to consider when judging a Butterfly koi is the base variety. For example, a Butterfly Kohaku must follow all the rules for a Kohaku before the Butterfly qualities are even considered. In addition to this, the butterfly qualities are very difficult to judge themselves and often judging just comes down to personal preference.


Mixed Butterfly koi (Tosai) from breeder Suda

One of the interesting things about Butterfly koi is to do with the growth and development of the fish as it gets larger. Normally, when a koi gets to around 3-4 years old, it reaches maturity and its growth slows down. Typically, a koi will continue to grow and get bigger for its whole lifetime, but it is at this age that the growth slows dramatically compared to the first few years of its life. The Butterfly koi grow and develop in the same way with regards to their body but not their fins. In fact, once a Butterfly koi reaches maturity, the fins and tail start growing at an even faster rate than when the koi is young! The fins will continue growing and developing dramatically for the rest of the koi’s lifetime. This means that the older the koi, the longer and more impressive the finnage is. The oldest Butterfly koi are often compared to long dragons with the way they glide through the water. Unfortunately, this means that you cannot specifically judge a Butterfly koi on its finnage as the length of the fins in relation to the body is dependent entirely on the age of the fish. That being said, a good body to fin ratio for a Tosai butterfly koi (up to a year old) is 1:5. For a Nisai butterfly koi (between 1 and 2 years old), it is 1:4. And, for a Sansai butterfly koi (between 2 and 3 years old) the ratio is 1:3. For a mature koi, the ratio should be at least 1:3 but could be up to 1:1 when the fins and tail are as long as the body of the koi!



Butterfly koi are a truly stunning koi that will stand out in any pond for their grace and beauty. The Butterfly fins and tail have been developed in almost every koi variety now so there really is a Butterfly koi for everyone! Take a look at our current stock of Butterfly koi here: