Koi Betta Fish – Facts & Profile

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Yes, betta fish specifically named after Japanese koi fish do really exist. And if you are guessing that they got their name thanks to amazing coloration, your guess is absolutely right.

Indeed, koi betta fish are basically one of the many selectively bred variations of betta splendens, particularly in relation to their color genes. The koi gene is somehow an upgrade of the immensely popular marble gene, but this time focused on creating orange, red and black patches across their bodies.

If you are intrigued in finding out more about this amazing breed, here comes the profile, along with important facts.

Also Read: How Much do Betta Fish Cost?


With koi being a primarily color-related variation of betta splendens, the biggest difference from other betta types is certainly in these colorful patches all over their usually iridescent bodies.

They really do resemble a lot to original koi pond fish. When it comes to other characteristics, they are remarkably similar to simple betta splendens.

In fact, koi versions usually feature shorter tails and fins. If one wants to compare their body shape, we could say they look quite similar to plakat bettas, other than the koi coloration. Therefore, this makes them extremely agile but also less prone to fin rots or other fin-related complications.

Male specimens mostly feature stronger coloration when compared to their female companions. Additionally, with the koi gene being jumping just as the marble gene is, there is a strong possibility of these fish developing color patches across different parts of their bodies over time.

An average koi betta fish will grow up to 3 inches in length and they usually live around 3 years when kept in captivity. And seeing them in captivity is usually the only place to spot them, as they have been selectively bred and are therefore not naturally present in the wild.

Behavior & Personality

Koi betta fish are considered to be in the ˝more aggressive˝ category of betta types. They have quite the temperament and are happiest when housed alone, into a single tank.

Since they are usually with shorter fins, they are super-agile and make the amazing little fighters. On top of that, they can often try jumping out of tanks and they can succeed if there is no lid at the top.

When it comes to breeding behavior, this is exactly the same as in other betta splendens. They create bubble nests on the water surface, where they keep their eggs safe until they are ready to hatch.

Care & Requirements

With the koi variations being mostly focused on the coloration instead of tail shape or behavior, there is absolutely no extra care which these fish require.

Simply house them into individual tanks to avoid aggression towards other fish and always keep their water warm and impeccably clean.

Although their tails and fins are usually shorter, please avoid placing any rough or spikey object inside their tank. And make sure there are plenty of live plants to keep them interested and to increase their feelings of safety and protection.

Food & Diet

Just as most other betta fish, koi bettas are also carnivorous. Therefore, please ensure that their pellets or flakes which will act as their regular basic meals are high-quality and protein-based. This is extremely important among koi betta fish, in order to maintain their super-bright coloration.

Adding to that, all betta fish can be quite the picky eaters. That said, it is necessary to include a variety of meaty treats into their diet plans, so they do not get bored and start refusing food.

Frozen brine shrimp and bloodworms are great, but they will certainly be happier when you provide them with live food. After all, they are designed to hunt. Koi bettas, just like other betta fish will hunt anything that moves in the aquarium including snails and shrimp.

Betta fish are generally quite vulnerable when it comes to digestive issues, and they can easily develop dangerous constipation or bloat if overfed. Therefore, please always feed your tropical pets such meal sizes which do not exceed the size of their eyes.

This is considered to be an amazingly helpful thumb rule for all betta owners, as betta eyes are proportional to their stomachs.

Health Problems

Thanks to their mostly shorter fins and tails, koi betta fish are luckily less prone to developing fin rot. However, they are still quite susceptible to suffering from swim bladder disease at some point. Nonetheless, swim bladder can be efficiently treated if spotted during an early enough stage.

Other than that, koi betta fish do not tend to be more health-sensitive than other selectively bred betta types.

Unfortunately, they are all subject to developing some sort of tumor eventually, but this is the case with all animal breeds which have been interfered by humans that much. Sadly.


  • Apart from the koi genetic coloration type, there are several more which are part of the marble gene family: nemo, galaxy, fancy, tiger, candy and samurai.
  • Those fish that are referred to as ˝true koi bettas˝ can change their patterns and colors several times through their lifetime, thanks to the defective gene which causes marbling.
  • Although most of the available koi versions are plakats or similar, this gene has been successfully implemented into most long-tail versions as well. These include feathertail, over halfmoons, spade tails and other.
  • Although aggressive towards other species, female koi betta fish tend to function very well in groups and are one of top choices today for creating betta sororities.
  • Betta fish which own the koi marble coloration gene are usually more expensive when compared to those of other coloration.

Wrapping Up

Everyone knows how Japanese pond koi fish look like. They have amazing coloration which looks spectacular while flowing. But not only. Did you know that each coloration pattern of such fish has a special meaning in Japanese culture?

Well, it is not hard to realize why betta fish enthusiasts wanted to replicate such color patterns to these tiny fish as well.

And luckily, being that focused on color genetics, breeders have been less focused on modifying their tail length, making them less prone to related diseases.

Author Image Fabian
I’m Fabian, aquarium fish breeder and founder of this website. I’ve been keeping fish, since I was a kid. On this blog, I share a lot of information about the aquarium hobby and various fish species that I like. Please leave a comment if you have any question.
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