Can You Have Just Two Koi?

Koi fish are known as one of the most beautiful pets you can have, and if you treat them well, they could become lifelong companions. If you are looking to make a koi pond or purchase koi as pets, it is vital to understand as much about them as you can. Strangely, the lifespan of a koi fish depends on many factors, including companionship. So, can you have only two koi?

It is possible to have only two koi in a pond or tank when first starting. However, it is essential to note that koi are generally seen in between five and fifteen groups as they prefer company. If you do not have enough capacity, it is best to expand and buy at least three koi at the start.

There are many guidelines and tips for keeping your koi happy and healthy. Along with the fact that koi seek companionship with other fish, the amount of space and water you have for them to swim in can also affect how many koi you should have.

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Can You Have Only Two Koi In A Pond Or Tank?

Koi are known for being social fish and prefer swimming in groups of between 5-15 fish if the space allows it. With that in mind, koi can survive and live exceptionally long lives in smaller groups or pairs. 

Koi fish must have at least one other koi for companionship as it improves their quality of life and helps them live longer. Lone Koi fish are known to die earlier than koi found in groups. Koi fish have social tendencies, and when kept together with other koi, the lifespan of your koi can expand exponentially. 

Along with the natural need for companionship, other things could also influence the lifespan of your koi if there is more than one fish. The size of the tank or pond you keep your koi in is just one of the aspects you will have to consider. Their food and water quality can significantly affect your koi and extend or shorten their lifespan.

Koi are friendly towards other fish, and they can get along well together. However, you will need to research this topic before buying a different fish species to live with your koi, as koi are considered messier, and some fish can not live in the same pond or tank.

How Much Space Do You Need Per Koi Fish?

Since koi can live for a long time and grow exceptionally large, experts will always recommend that you keep them in a pond rather than a tank. Though you can keep koi in a tank for a while, they are known to outgrow their tanks and will therefore stop growing.

Koi in tanks are also said to live shorter lives when compared to those in ponds. There is a general rule that koi have a minimum amount of water needed depending on their size. 

The size of your koi and the amount of water needed will naturally affect how many koi you can keep in one area. Keeping koi in 10 gallons of water for every inch of the koi’s length is suggested as a minimum guideline. You can also keep your koi in larger areas, as is recommended and said to be better for their health.

The recommended area you would need for one koi is enough to hold 250 gallons of water. The space required to retain this amount of water is around 34 cubic feet. Experts suggest that you keep to these size standards to avoid the need for expansion while also allowing your koi to reach full size without having too little space to swim.

How Much Space Do You Need For Two Koi Fish?

Based on the estimates seen above, if you wish to make a pond for two koi with enough room to grow and live healthily, you will need an area of around 68 cubic feet in total.

If you wish to extend your pond at a later time, you should still allow the koi at least 10 to 15 gallons of water per inch of fish. 

If you do not extend the size of your pond, your koi could stop growing, which will negatively affect their health and possibly their lifespan. 

How Many Koi Fish Should You Have?

Because koi are social animals and need companionship to help them live longer, you should aim for at least three koi when first starting out. Not only will this allow the fish to have fellowship, but it also means that if one were to die, your remaining koi would still have a companion. 

Though there are benefits to having at least three koi, many other things can determine how many koi you should have. The size of your pond is a significant factor to remember when buying koi or deciding how many to buy. If your pond or tank is too small to create the needed environment for your koi, they might suffer in the long term.

You should also consider the amount of koi feed you need in relation to how many koi you have. Depending on the amount of koi you have, keeping koi can cost you quite a bit of money by feeding your fish. It would be best always to consider your koi feed when buying koi for your pond. 

Can You Have koi Of Different Sizes?

Since koi are technically omnivores and can (and have) eaten smaller fish, you might wonder if you can keep different-sized koi in the same area. 

If you are willing and can put in the work to give your koi the right amount of food and a good and stable environment, you should be able to keep other fish and smaller koi with your larger variety. Koi are omnivores and eat smaller koi if they are not getting enough food, or too many koi live in one area.

If you provide your koi with the right amount of space and food, you should be able to keep both big and small koi together. This is especially useful to know if you have lost some koi in the past and are looking to replace them. Experts recommend that for the sake of companionship, your larger koi should have at least one companion around the same size.


Though you can have only two koi, the recommendation is that you get at least three. The reason for this being if one of your koi fish suddenly dies, the remaining koi will not be left alone. Koi who have companions and the right amount of care can live much longer lives than those with no companions.

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