8 Fish That Can Live With Koi In A Tank – Koi Tank Mates

Selecting tank mates for koi is crucial are coldwater carp type fish. You have to consider a lot of things before you put a fish with koi in a tank.

It is better to keep other coldwater fish that has the same size and diet of a koi. But you can select some of the tropical fish with koi as you are putting them in a tank, not in a pond. Because here temperature is not an issue as you can easily control it.

In this article, you will learn about some species of fo fish that can live with koi in a tank.

Things to Consider Before Selecting Koi Tank Mates

  • The first thing to ensure is that the fish isn’t aggressive so that it doesn’t attack the koi. Keep social fish with koi and other fish so that they live happily.
  • Make sure the size of the fish is nearly similar to koi.
  • The temperature requirement should be the same. Or, at least the selected fish can thrive at the ambient temperature for koi.
  • Make sure the selected fish doesn’t require more care than a koi because you may find it hard fulfilling their demand.
  • The selected fish species shouldn’t fight with koi for food.
  • Stock large fish with large koi and small fish with small koi.
  • It is better if the selected fish species is a bottom feeder.
  • It is better if the selected species has the same characteristics of a koi.

Fish That Can Live With Koi In A Tank

Barbel (Barbus barbus)

Juvenile barbel

Barbels are native to Europe. They can reach up to 4 feet although most of them are 40 inches. The lifespan of Burbel is up to 20 years. As their size are similar to koi fish and exhibits the characteristics of Carp, they are good as Koi tankmates. The temperature requirement and diet are almost the same.

They are a bottom feeder and hence keep the aquarium bottom clean by eating the excess food left by koi fish. As the size of Barbel fish is large, you have to keep them with adult koi fish. Also, the tank size needs to be large enough. You also have to maintain a good flow of water in the tank for them.

Barbs (Barbus tetrazona)

Nigger Barb Fish

Barbs are originated from Sumatra and Indonesia. They have a slender body and can reach up to three inches in length. They are peaceful and not territorial. therefore they are good as tank mates for Koi and Goldfish. As they are small, they don’t require that much water volume.

If you like Barbs, then you can buy them online here.

Golden Barb Fish

Barbs can live up to 6 years in the tank if the water quality and a good diet are ensured. They are Omnivorous hence the diet is the same as Koi fish which is a major advantage when you keep them with koi fish. Barbs are colorful fish and available in a large verity of color. This makes them more beautiful when they are kept in a tank with good lighting. Also as they are small, try to keep at least 5 of them together.

Catfish (Siluriformes)

This may sound weird to keep koi and catfish together, but there are many species of Catfish that will live happily with koi for a certain age. Although catfish are tropical fish, they have the ability to live in a wide range of temperature. The following catfish breeds can be stocked with Koi Fish in a tank –

  • Bandit Cory Catfish
  • Bumblebee Catfish
  • Columbian Shark
  • Iridescent Shark
Bandit Cory Catfish
Bandit Cory Catfish
Bumblebee Catfish
Bumblebee Catfish
Colombian Shark
Colombian Shark
Iridescent Shark
Iridescent Shark

However, there are some disadvantages of keeping a catfish in a tank with other fish. First of all the catfish are tend to disturb the bottom of the fish tank. Secondly, they are the bearer of parasites and diseases.

Again you should only keep the Iridescent Shark with large adult koi fish. If you keep an adult Iridescent Shark with small koi or other smaller fish, it will eat them up. So, be careful when you keep them together.

Goldfish (Carassius auratus)

Goldfish are most commonly kept with koi fish in the tank. The reason fishkeepers keep goldfish with koi in a tank is their characteristics are the same. In fact, goldfish are the nearest to koi. Both are coldwater fish and the diet is almost the same.

Comet Goldfish
Comet Goldfish

But Comet Goldfish from this link.

Again goldfish requires less care than koi fish. That means they don’t need any extra care when you put them with koi in an aquarium.

There are many types of goldfish available. But you can’t any of them with koi in a tank. Why?

Because, if your goldfish is small and the koi is large, the koi can eat the goldfish. So you have to be selective and careful while putting a goldfish and koi together.

Shubunkin Goldfish
Shubunkin Goldfish

Buy Shubunkin Goldfish from here.

You can put Comet and Shubunkin Goldfish with koi fish. They are large and strong enough to live with koi. But, never put a baby or fancy little goldfish with koi in a tank.

Golden Orfe (ILeuciscus idus) 

You can barely differentiate between a Golden Orfe and a Golden Koi fish when they swim. Their body characteristics are almost the same as a Koi fish. Although they are bottom feeders, they also swim in the tank and pond surface like koi.  Also being a bottom feeder, the keeps the tank bottom clean.

Baby Golden Orfe
Baby Golden Orfe

Golden Orfe is river fish. They require good water quality. Therefore, if you keep them with Koi in a tank, you have to maintain a good filtration and oxygenation of the water. Also, try to keep at least 3 in a group as they are social fish.

Tench (Tinca tinca)

Tench are called doctor fish. Do you know why?

People believe that they are physicians of fish. They also look somewhat like doctors because of their body shape. They can reach up to 70 cm and weighs up to 7.5 Kg. They are peaceful and social fish. Hence keeping them with koi won’t create any problem.


As tench are bottom feeders, they often tend to disturb the bottom of the pond and tank. Therefore, if your tank has fine sand in the bottom, you shouldn’t stock it there.

Pleco (Hypostomus plecostomus)

Pleco is a tropical fish that goes well with koi. It is very hardy and suits well for pond and aquarium. Plecos are widely kept by the fishkeepers because of their attractive colors.

Gold nugget pleco
Gold nugget pleco

There are two problems associated with keeping pleco. The first one is they can latch with slow-moving fish. And secondly, you have to maintain the tank temperature above 55 F as they can’t thrive at low temperature.

Sturgeon (Acipenseridae)

Sturgeon is a family of fish and there are 27 species in this family. Among them, 4 species are about to extinct. It is illegal in many places to catch wild sturgeon. Their evolution goes 245 to 208 million years back.


Sturgeon can get really big in size and weight. Although aquarium sturgeon will live happily with koi, their irregular movement can disturb the koi and the tank bottom. So be sure you have a large tank before you put them with koi.

69 thoughts on “8 Fish That Can Live With Koi In A Tank – Koi Tank Mates”

    1. Hey Paul,
      Although Gourami fish are aggressive, due to their smaller size, the can’t harm Koi fish. But you shouldn’t keep gourami with large adult koi fish, koi may eat them.
      Again temperature is also an issue because gourami is a tropical fish and koi is a coldwater fish. So, make sure the tank temperature is suitable for both of them.

  1. My fish tank which is rather big has the following fish leaving with the koi’s. Do you see any issue?
    1. Molly
    2. Clown loach
    3. Rummy noise
    4. Mono
    5. Pleco
    6. Silver shark
    7. Parrot fish
    8. Silver dollar

    1. The Mollies may face some problems living with these fish. Also, I’m afraid of the parrotfish. What type of parrotfish do you have? Some parrotfish can be territorial and can harm small and weak fish species.

      1. I had 4 silver sharks in my aquarium and after one week i added 4 koi carps then koi carps started chasing my silver sharks so that aquarium is clumsy everytime. Is koi an aggressive fish? I thought it is peaceful fish so i added it with my peaceful silver sharks

    1. Yes, you can keep the telescope goldish with these fish. But make sure the goldfish aren’t too small compared to these fish.

    2. I have 14-18” kois in my pond. Put 2 black moor telescope 4” goldfish in the pond. Next morning the telescope eyes were missing. The kois ate them.

  2. Ive 2 koi fish 2 milky koi n 2 moon tail molly n 2 swordtail they can be happy with each other or it harms them? plz reply it m new In this so

    1. I think silver dollars can create some problems. Are they big in size? If yes, they can behave aggressively towards other.

    1. Betta fish are territorial. If the koi are large in size then the betta will not dare to fight. But if koi are small then betta may try to fight. Again the betta may try to harm the fins of koi. Therefore, I will suggest you keep the betta in a separate tank.

  3. I’ve two koi fish in my tank, and they seems to be very afraid whenever I approach. Is their anything wrong with them? As I know that kois are very friendly fishes. I’ve following fishes in my tank
    1. Silver Dollar
    2. Irridescent shark
    3. Angel fish
    4. Pleco

    1. Try to make a friendship with them by spending some time and feeding them. I hope it won’t take long for them to get used to.

  4. I have 3 koi and 2 comet goldfish in my aquarium. I had added some small fish like tetras, mollies, platys and 2 red tail black sharks. I had to take out the mollies and platys as they kept on harrassing the bigger fish and my koi lost some scales. Do platys usually do that?

    1. As far I know platys are peaceful. They aren’t supposed to do that. Try to add some element in your aquarium so that they can play with that and don’t harrase the bigger fish.

      1. Can you have tank mates with currently have: 2 goldfish and looking at purchasing
        A tank that has rainbow shark, glow fish Diane, ruby red Platty, ruby red barb, and balloon molly. Can you put them together as tank mates?

    1. I’m afraid you can’t keep them with koi or goldfish. Although Bichirs aren’t aggressive requirements for them and koi are totally different.

  5. My Koi is losing his/her tank mate. They are VERY attached. I have been nursing the butterfly koi for a long time. The butterfly koi appeared to doing really well but took a downturn. It is wrenching watching it die and the other koi gently swim by lightly brushing against the struggling fish. In the past it would just stay by its side when it was weak. Any suggestions on how I can help this large koi after the tank mate is gone? It is a 150 gallon tank with just these two fish. Water changes are relatively easy with a hose. The surviving koi is over a foot in length. I have not been able to find a well tended large safe pond to re-home the koi and now that Winter is approaching it is best to wait until warming weather in the Spring.

    1. I feel very upset hearing that. The best thing you can do is find a tank mate for your fish as they are very social and love companion.

    1. I’m not sure as I don’t know much about the behaviour of Paroon shark with other fish. You can stock 2-3 koi with them and observe their behaviour.

  6. I have seven adult fantails( fancy tail) goldfishes in my tank. Recently, I pit an average size koi fish in it. My goldfishes started to die each day. Should I separate the koi from them?

  7. I have 5 carp and 2 small size milky carp companies with 2 black tetra( is it safe? ).
    Any suggestion, which fish I should put into my tank, so that all live happily.

    1. Keeping milky carp with tetra is safe as long as the milky carps aren’t hungry. Just give the milky carps enough food.
      You can keep any species of peaceful coldwater fish that have compatible sizes.

  8. This is probably a silly question, but if lionfish and butterfly koi had the same temperature & water requirments would they be fine together?

  9. I have a pond, some 70-80 gallons. I have a few goldfish and three koi. I have two eels that I did not use for fishing, as bait. I don’t know if the can be compatible with the above. As well can they live in
    in fresh water.

  10. My fish tank which is rather big has the following fish living with the koi’s. Do you see any issue?
    1. Guppies
    2. Swordtail
    3. Light tail
    4. Cat fish
    5. Platties
    6. Zebra

  11. Hi,

    My Mom bought a 1 small size Koi around 5-6 inches. Can I put him along with Tetras, Swordtail, Danios and Green barbs? Thanks!

  12. Ebenezer Caballero

    I have Goldfish (oranda, demekin) + koi. Can I still add some small fish? And if yes, what small fish can I add? Would zibra or neon tetra be okay?

  13. Hi, I have a 720 US gallon fish pond. I plan to have 6 x Butterfly Koi, 6 x Comet/Shubunkin, 4 x Gourami, 2 x Pleco, 10 x Barbs and 10 x Clown Loaches. Firstly, are they compatible? And secondly, is my fish pond big enough to accommodate all of them?

  14. Hi, I have a young koi that hasn’t been around fish in a while and I want to put plecos in the tank. I’m wondering if my koi will attack the pleco.

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