koi betta fish

Koi Betta Fish : A complete guide and Care Sheet

Holding the hearts of most fishkeeping hobbyists in the world, Betta fish with their unique patterns and colors are some of the most popular and in-demand fish right now. The Betta fish family consists of a vast variety of colorful, astonishing, and beautiful patterns, colors, and personalities. However, the most discussed type among novice hobbyists would, no doubt, be the Koi Betta.

Therefore keeping up with the tradition we have curated this guide to lead amateur and seasoned fishkeepers to have a healthy and happy koi betta, a freshwater fish, in their fish tanks.

What is a Koi Betta?

Koi Betta fish, the scientific name “betta splendens” is a variation of Marble Bettas with multiple color patterns in different combinations like plakat betta and galaxy koi betta fish. The extreme resemblance with the Koi Carp or Koi fish is the reason for its commonly known name that Koi Betta. 

Origin of Koi Betta Fish

Koi betta fish is a beautiful and unique freshwater species belonging to the Osphronemidae family and native to Southeast Asia including India, Thailand, and Bangladesh. Though Koi Betta Fish normally known as marble betta fish originate from Asia; you can find them for sale all over North America today. When people think of koi bettas, they usually picture the red or orange-colored variety with long flowing fins. However, there are many varieties of wild betta that come in colors such as white, brownish-gray, black, and gold. They may also have short fins as the Showa koi bettas do.

Koi Betta belongs to the Betta family of fish. The koi betta is also called the marble ‘Siamese fighting fish’ because of its aggressive nature. This type of Betta was originally bred to fight other male Bettas for sport and not for survival purposes as their wild counterparts did.


The koi betta is a member of the gourami family and has an elongated body with large fins. This is as opposed to the traditional Betta fish appearance that has a compressed body shape and high dorsal fin gills and a labyrinth organ. each color pattern and combination of koi betta fish is unique and astonishing making it the most popular choice for a person willing to be a fishkeeper.

The appearance of Koi Betta is very similar to the Marbled Betta fish but with much more distinctive coloration on their scales that make them an ideal aquarium species for beginners as well as experienced hobbyists alike. You’ll find that koi bettas come in many colors including black, brown, white, red, and many more.

Koi Betta Fish
Fancy koi galaxy betta source image: @npdstock Freepik

Difference between Male and Female Koi Betta

The males will have long flowing fins while females may not necessarily have long fins as they tend to be shorter than males. The koi betta is one of the few species in which there are obvious differences between male and female betta specimens that can be recognized at a glance by an experienced fishkeeper. The easiest way to distinguish gender from each other would be through their fins but also look for bright orange or pink coloration on the anal fin in mature adults as this is another identifying feature present only in adult males. However, you cannot make any assumptions about age based on these colors.

How long does a koi betta get?

3-7 inches. Koi Betta range in size depending on their age, breed, and sex.  When they are first hatched, koi bettas can grow up to an inch a month! However, by the time that they reach adulthood (about three years), most koi Betta fish will be about five inches in length. Koi Betta Fish belonging to different breeds may vary slightly from this range but these numbers do provide a good estimate of what size you should expect your koi betta to become throughout their life span.

Koi Betta Lifespan

5-10 years. Koi Bettas can live up to 10 years in captivity depending on how well the owner takes care of them and provides nutritious foods as well as adequate living conditions.


Koi bettas are carnivores and feed on invertebrates like worms and insects in their natural habitat but should be given some type of protein-rich food source at least twice a day when they’re being kept in your aquarium. This can include freeze-dried bloodworms, brine shrimp, krill, and plankton among other options depending on availability within your region. Different types of flakes with high levels of vitamins are also good foods to offer them every now and then though these do not provide as many of the nutrients that koi bettas need to remain healthy and active in your fish tank.

READ  Best Aquarium Fish for Kids and Beginners | Reviewed 2020

Behavior and temperament

Koi Bettas are known for being very aggressive fish when it comes to defending their territory against other male Betta Fish. In fact, this is what made them such good competitors during fighting matches between males back in Asia where they originated from. They will attack anything that enters their “territory” which may include you if you attempt to handle them while they’re resting inside a bowl or aquarium. Koi Betta’s temperaments can vary greatly: some have been trained by owners through positive reinforcement techniques while others still behave aggressively towards anyone who dares approach a water container or habitat with their presence.

Is koi betta aggressive?

Yes. As mentioned before Koi bettas are aggressive but those that are kept in tanks with other peaceful fish species will not typically attack other aquarium fish but may be very prone to picking fights among themselves or even against the aquarium owner if they feel threatened by a person’s hand coming close to them while they rest on the bottom of an aquarium. Most owners have also found that it is best to keep only one male koi betta fish per tank as this can prevent violent encounters between two males who are trying to compete for territory within your home environment.

A female koi Betta fish has been known, however, to show aggression towards each other and toward people more often than her counterpart especially when she wants something like food or attention from you during feeding time. If you do want to keep a koi betta as a pet, be sure that your aquarium is big enough for them and has plenty of hiding spaces within the rocks or plants so they can retreat in case another individual enters their territory while they’re resting.

Aquarium and Water Parameters for a koi Betta

Koi Bettas are sensitive fish that require special care when it comes to water temperature, pH levels, and overall environmental conditions including adequate lighting inside an aquarium habitat where these fish will reside unless otherwise noted by the breeder or owner prior to purchase.


They thrive best at temperatures between 76˚F (24˚C) all the way up to 82˚F (28˚C) but can survive at slightly lower or higher temperatures as well.

Ph Levels

When it comes to pH levels, Koi bettas prefer a range of around 74-79 with the optimal level being between 78 and 80 depending on where they are kept in your aquarium.

Water conditions

The water conditions of a koi betta fish are very important. It prefers soft or slightly hard water with neutral pH levels as far as salinity goes, they do not require high salt content due to their brackish nature; only 0.015 percent is enough for them. For substrate, sand that does not contain any impurities such as calcium carbonate or magnesium oxide will suffice since these two ingredients are harmful to Koi Betta fishes. Water hardness for Koi Betta fish should be between 5-35 dGH.


As for lighting conditions: koi Betta fish will require some form of sunlight whether from an artificial light source like fluorescent bulbs or through exposure to natural sunlight during daylight hours so make sure you have adequate filtration and water changes taking place within their habitat if you’re keeping them indoors without access to direct sunlight throughout the day.

complete care guide for Koi Betta
Care Guide for Koi Betta Fish

Koi Betta Fish Tank Mates

There are some peaceful fish species out there who get along well with koi bettas but you need to be careful about what kind you choose as not all safe combinations will work in your favor! We’ve listed the most popular choices below into three different categories tanks that hold up to three gallons of water, tanks that hold five gallons, and ten gallons of water.

Tank Mates for 3-gallon tank

As 3 and 3.5-gallon fish tank has such small space, it is recommended to not overstuff it with other long and big fish species. Koi betta tank mates for a 3.5-gallon fish tank can be Ghost shrimps and snails.  However, ghost shrimp and snails are not a good idea for their own reasons. Snails can be kept in tanks as they do not require high levels of oxygen, unlike fish. Ghost shrimps on another hand clean up leftover food from your tank which is great but you have to make sure that no one has eaten them; which being such small creatures can happen easily. They also need to stay under rocks or plants otherwise they will get scared and stressed out, sometimes leading to death. Other than these two species there really aren’t many suitable Koi Betta tank mates for three-gallon fish tanks.

READ  How to Reduce Nitrate levels In an Aquarium?

Tank Mates for a 5-gallon fish tank

It is not recommended to keep koi betta tank mates for your fish tanks in a five-gallon tank as it is too small. However, if you do plan on keeping other species of fish together with Koi Betta then there are some options available.

Your choice of koi betta tankmates would be livebearers and tetras. This works well because different types of tetras can coexist peacefully along with Guppy like livebearer fishes which will add more color into the aquarium. Other than these two choices you cannot really go wrong adding any non-aggressive community-type catfish or minnows to your best friend’s home. As they get bigger over time, they need bigger accordingly so an upgrade is always good.

Tank Mates for a ten-gallon tank

When it comes to tanks that are larger than five gallons, you have more options available as far as koi betta tank mates go. They won’t be targeted by your Koi or other fish either so they can coexist together very well and live in harmony with each other without any problems occurring over time. Minnows like rosy reds, oranges, shiners, etc. are quite colorful and add life to the aquarium while peaceful community catfish species make great pets too! Other types of Tetra which come from South America also work well alongside Guppies because they do not require special care, unlike bettas who need special care and attention.

Some of the other koi betta tank mates that can be added to your ten-gallon fish tanks are White Cloud Mountain Minnows, Killifish such as rainbow or guppies which are livebearers but they lay eggs instead of giving birth as Guppy’s do. They also tend to get on with each other very well in a larger environment because there is more room for everyone compared to small five-gallon tanks where only one small species can coexist at any given time. Other than this you have many different options available so it’s just a matter of doing some research before setting up your new best friend’s home!

worst koi betta tank mates

You mustn’t keep other species with koi betta fish in the same tank for several reasons. First, they are aggressive and will fight to the death if kept together so it’s best to avoid this from happening at all costs! Second, their behaviors have been known to change drastically when placed into smaller tanks as opposed to large aquariums which make them more territorial because there is less space available than what they were used to.

Lastly, female but especially male bettas can become even more aggressive towards other creatures once she spawns or he releases his sperm during the breeding season; which also makes it difficult on your end to remove them without harming either one of them in some way shape or form. So, it is always recommended to keep koi betta fish alone in a larger tank so they can live out their lives peacefully without any problems occurring.

common diseases in Koi Betta

Velvet disease or oodinium is one of the most common types of parasitic infections that affect your male and female koi bettas at some point during their lifetime whether you notice it or not. It does not harm them but merely gives off a yellowish appearance on the skin which looks like small golden dots all over their body, head, and fins. However, if left untreated this condition will get worse until it begins covering more than half of its entire surface area. 

Koi betta is also susceptible to ich (Ichthyophthirius multifiliis) even though it’s not really considered a “disease” per se; more like an infection that affects both saltwater and freshwater aquarium species which causes small white ick with a black dot. In most cases when ick is contracted by your koi betta fish it will affect their gills and fins which can be quite devastating for them in some instances where it becomes difficult to breathe, eat or swim properly.

How to breed Koi Betta Fish?

Breeding Koi Bettas has many benefits, not only can you produce your own supply of baby fry but the male will also display his most vibrant colors during this time making him look majestic against the backdrop of clear water with lots of green for plants for hiding places. 

READ  Bristlenose Plecos: A Complete Care Guide of Bristlenos Plecostmus
  1. Keep the pair separate

    Firstly separate your breeders from each other before starting the process. This allows them to calm down and get used to their new surroundings so they don’t attack each other the minute you put them together.

  2. Choose Fish Tank

    The biggest tank for these guys is 20 gallons long, however, if this isn’t possible then anything over 14 gallons will do but it’s advisable not to go much smaller than that because of space issues with moving around as well as oxygen levels getting too low under those circumstances. The easiest way is putting one male with two females in such cases or if you breeding just one Koi Betta then use an even larger tank like 30-40 gallons. although again make sure there are lots of hiding places and places for the fry to feed.

  3. Add gravel

    You should also get some gravel and treat it with a couple of drops of aquarium salt or whatever you use, just make sure it’s safe for fish before adding any new tank mates. otherwise, they will die too! Make sure all your equipment is working properly; this includes water filtration which needs to be up to par because if not then there’s no way these guys can stay alive in such small quantities of water

  4. lighting

    The best time to breed them would be springtime when natural light levels are around 12 hours per day. If you don’t live in an area where the sunlight hours are long enough then its easy to get artificial lights for your fish tank but make sure they cover at least 12-14 hours of light per day (over 50 watts) and that there is no natural lighting getting into the water because otherwise, it will turn murky green within days!

  5. Check Diet and water conditions

    too much food just before breeding can actually have a negative effect so it’s best not to overfeed them right before starting up the process. The male should look healthy and strong while the female has more rounded bodies filled out nicely. these guys are not the best when it comes to showing off but in my experience, they are much more aggressive than other breeds which is why you have to be very careful with them.

  6. Wait

    Once all set up then just sit back and wait. after about five days there should only be one left alive because remember Koi Betta males don’t see well and have a tendency to eat the eggs. so don’t be surprised if you find none left after five days!

  7. Post Breeding Care

    After the breeding process is done take out all plants as they will rot from being used as spawning mops. especially java moss which doesn’t do too well on its own. The fry should hatch within 24 hours of fertilization but some can go longer periods without food, however, small brine shrimp works wonders for this breed because their mouths are very tiny at birth.

How expensive is a koi Betta?

A koi betta is generally considered to be one of the most expensive fish in a freshwater aquarium. Their color, size, and rarity all play into how much you will have to pay for them as well as where they are coming from, local pet store or online shopping cart. However, if you purchase your new friend from a local shop or breeder expect to spend $30 – $100 depending on their age and unique features such as Doitsu coloring or other rare types that may not be available at any given time.


So there you have it! A complete guide about what these wonderful creatures need to stay healthy throughout his/her life span which should last roughly around five years once fully grown. In general, Koi Betta fish are relatively easy to care for and make excellent pets considering how many colors, energy, and life they bring to your aquarium space.

Koi bettas can be a bit expensive but if you keep their living conditions clean as well as provide them with proper food they are very fun to watch swim around the tank while eating some of it along the way!

Leave a Comment

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.