This Is What A Fake Koi Fish Is Called

Beautiful Yellow Butterfly Koi Fish swimming in the pond with other Orange and White Fish

There are almost 100 different varieties of koi fish. While most have many differences, they are all bred from the same original fish, a wild koi species found in Japan. However, another breed of fish has made its way into the world of koi. While this fish is now considered a koi species, it was once called a fake koi by Japanese and Western koi breeders. This is what was once considered a fake koi fish.

Butterfly koi fish, although beautiful, is a cross between a traditional Japanese koi and a type of long-finned carp found in Indonesia. Although butterfly koi are beautiful and many koi owners adore them, they were once regarded as fake koi due to their impure breeding and disproportionate fins.

Although butterfly koi are now regarded as actual koi and can be entered into some koi showing competitions, there was once a time when Japanese and American purists disapproved of this koi species because it was crossbred with a common Indonesian carp. This article discusses the history of the butterfly koi, the varieties of butterfly koi available today, and how to choose a great butterfly koi.

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Is A Butterfly Koi A Fake Koi?

A gold color butterfly koi fish on the surface of the water eating pellets
A gold color butterfly koi fish on the surface of the water eating pellets

To answer this, we must consider what a butterfly koi is first. A butterfly koi is a crossbreed between a regular koi and an Indonesian carp. This fish was first discovered and sold in the 80s. However, as the Indonesian carp is an ugly fish, it didn’t sell too well.

However, an American company started crossbreeding this carp with various regular fin koi and discovered that although the longfin genes are dominant, the color is not. The result was a colorful fish with long fins. Initially, these fish were regarded as mutts and not appreciated by koi purists. However, they became more accepted by the koi breeding community with time.

So, calling a butterfly koi fake might be a stretch, as other highly prized koi varieties are also crossbred with carp species, such as Shusui koi. However, butterfly koi were known as a species of fake koi for many years.

What’s interesting about the butterfly koi is that their fins keep growing until the blood vessels cannot support their growth anymore. Research suggests that the Indonesian carp lacks the receptors that tell the fins when to stop growing.

While this is a strange characteristic, the result is beautiful, wing-like fins. Many varieties of butterfly koi have been bred since the original carp and koi mix. These are some of the most popular butterfly koi varieties:

  • Ghoshiki
  • Kumonryu
  • Kohaku
  • Asagai
  • Sanke
  • Utsurimono
  • Shusui
  • Showa
  • Sorogoi
  • Black Beauty

While all these varieties are beautiful, Sorogoi and Black Beauty butterfly koi deserve special mentioning.

What Are Sorogoi Butterfly Koi?

Sorogoi are grey, and some have Fukurin scales. Fukurin scales mean that the scales have a black outline, creating a netted appearance on the fish. Pair the grey color and netted features with long, winged fins, and you have a truly remarkable fish.

If you can find a Sorogoi butterfly koi, you will undoubtedly pay top-dollar for it, but it will add a unique feature to your pond. Furthermore, if you intend to enter your butterfly koi into competitions, a sorogoi butterfly koi will surely be a good fit.

What Are Black Beauty Butterfly Koi?

Black beauty butterfly koi are the rarest type of butterfly koi. However, they are also likely the most beautiful. These koi are pitch black, and their long fins make them look like dragons or shadows swimming around in the water.

Although black beauty and Sorogoi butterfly koi are the rarest and most beautiful butterfly koi available, the other butterfly koi varieties are not to be overlooked. Any butterfly koi will make an excellent addition to your koi pond.

Now, you might be wondering how regular koi and butterfly koi differ from each other. These are the main differences between regular koi and butterfly koi.

What Is The Difference Between Koi And Butterfly Koi?

Butterfly koi differ from regular koi on three points: the length of their fins, the length of their whiskers, and their body shapes. For these reasons, some think that butterfly koi are fake koi.

1. Butterfly Koi VS Standard Koi Regarding Tail Length

Regular koi traditionally have broad, paddle-like fins. Their fins are only a few inches long. However, butterfly koi are a different story. Their fins don’t stop growing until the blood vessels can no longer support them. As a result, butterfly koi’s fins grow between 500 and 1000 times longer than regular koi’s fins.

2. Butterfly Koi VS Standard Koi Regarding Whisker Length

In addition to the fins growing longer, butterfly koi’s whiskers also grow longer than regular koi’s whiskers. In addition, butterfly koi’s whiskers sometimes form branches, adding to the unique look of these fish. Although this sometimes happens, most butterfly koi usually only have longer whiskers than regular koi.

3. Butterfly Koi VS Standard Koi Regarding Body Shape

The final aspect in which butterfly koi differ from regular koi is their body shape. Regular koi tend to have oval-shaped bodies. Their heads and tails are about the same size, and their midsections are slightly broader.

However, butterfly koi have more of a torpedo-shaped body. They are generally more slender than regular koi and taper off towards the tail end.

Although butterfly koi differ from regular koi in these aspects, they have similar colors and features to regular koi. So, what qualities must you consider if you want a unique butterfly koi?

How To Choose A Butterfly Koi

Butterfly koi have different patterns than regular koi. Various koi species have been bred with butterfly koi to develop crossbred koi species. However, as these species are meant to be a cross between regular koi and butterfly koi, you must also consider the features of a regular koi.

For example, when looking for a prime regular koi, you must consider the scale patterns and symmetry of the fish. The scales should be uniform in size and neatly aligned along the sides of the koi. The color markings should be symmetrical on either side of the fish. In addition, the fish should have no split fins, scars, or blemishes.

These characteristics determine the quality and price of a regular koi fish. The same factors apply when looking for a butterfly koi. However, you should also look for a butterfly koi without damaged fins in addition to these characteristics.

Butterfly koi often have damaged fins due to handling. Because butterfly koi are most prized for their long fins, it can be expected that this should be one of the things to look out for when buying a butterfly koi.


Butterfly koi are considered fake in some parts of the world, including Japan. Butterfly koi have long, beautiful fins that are 500 to 1000 times longer than regular koi. Although butterfly koi are not considered real koi by all, they are loved by many and are a very popular koi fish to own.

Butterfly koi come in many varieties. However, the rarest and most valuable varieties are Sorogoi butterfly koi and black beauty butterfly koi. Choose a butterfly koi with undamaged fins and symmetrical colors.


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