Can Koi Fish Live in a Fish Tank?

Can Koi Fish Live in a Fish Tank?

Koi fish are a common pet these days. Everyone loves their friendly personalities and bright colors. 

Plus, it is incredibly easy to pop into a pet store and grab a few of these fish from the super full and active tank display for cheap! 

They even sell the same size tanks nearby that the fish for sale are housed in, probably. 

Unfortunately, there is a common misconception related to this sales model that indicates that koi fish can be kept in a fish tank. 

Let’s take a look at why the answer to, “Can koi fish live in a fish tank?”, is “no”, and see if we can better understand why koi are not suitable for most tank enclosures.

So, Can Koi Fish Live in a Fish Tank?

While the answer is generally “no”, there are some special circumstances that do allow koi to be kept in a tank.

Let’s get into those before we learn more about why koi are not, in general, suitable for keeping in tanks.

Can Koi Fish Live in a Fish Tank

Can Koi Fish Live in a Fish Tank If They Are Small Enough?

Koi fish, when they are small enough, can be kept in a tank to quarantine them. 

This includes situations where you’re preparing to introduce a new koi fish into your pond and want to quarantine the fish for a period of time.

Ensuring that the fish is not sick or carrying parasites, or in times where a fish is sick or injured and needs additional care. 

In instances like these, you can keep the koi in a tank that is adequately sized for their length. 

The rule of thumb is ten gallons per inch of fish, so, for example, if you have a five-inch fish, you need fifty gallons of water.

If your fish is significantly larger than the size of the recommended tank sizing, you probably need to opt for a pop-up pool or koi pond for this purpose.

Can Koi Fish Live in a Fish Tank for Breeding

Breeding koi fish is something that cannot be done easily. 

This is because koi fish are very active fish in general and can easily beach themselves or end up fighting and hurting one another if left in a smaller tank. 

Breeding koi fish requires a lot of space and definitely calls for a larger sized setup. 

While many will not do this in a tank and will instead use a small pool or other enclosure, if you have the proper gallon allowance, it is doable.

Additionally, raising koi fry is possible in a tank. 

In fact, it is one of the best uses of a tank for koi fish and one of the only situations where “can koi fish live in a fish tank”, can be met with an easy yes. 

Having koi eggs hatch in a tank and raising the koi fry in the tank can give you easier access to monitoring them.

Ensuring they are growing properly, while also ensuring that you can treat and care for your fish easily should any issues arise. 

Koi fry are tiny so having them in an enclosed space is actually recommended in order to ensure they are not lost or eaten by other, larger fish.


Why Can We Not Keep Koi Fish in a Tank?

Koi fish are large fish. They require a lot of space to move around and are generally very active. 

Due to this, they cannot be contained in a small enclosure like a typical fish tank. There is a myth that a fish will only grow to the size of its tank. 

A koi fish can easily grow to be over three feet in length. 

This means that when the koi fish is kept in a tank and cannot grow to its full size, it is being stunted.

A koi not having room to properly grow is inhumane and can have some serious health effects. 

While the answer to “can koi fish live in a fish tank” is technically yes, it is not a good idea, nor is it good care practice. 

Koi fish that are kept in tanks in pet stores are generally very small and, while the tanks are often overstocked. 

They are bought quickly and removed from the crowded tank soon enough that it does not typically have a severe lasting impact on their health.

If you are going to keep koi in a tank, it has to be large enough to fit all of the fish you have. 

If you have multiple fish, that would be ten gallons per inch of each individual fish. 

As you can imagine, this likely becomes a very high volume tank requirement very quickly. 

While this can be a lot to require, it is simply the cost of owning koi fish, as when you have a pet you have to be able to provide proper care.

The Benefits of Properly Sized Koi Enclosures ​

Koi fish are truly an amazing species. 

They are friendly, interactive, and so much fun. 

Plus, they look absolutely gorgeous and vibrant, like works of art. 

Having them in a properly sized enclosure with filtration and all of the space to move around they could want will help to ensure they grow properly and become the pretty, gentle giants we know and love.

The properly sized enclosure contributes to the coloration of the fish too.

As when they are stressed or not living in optimal conditions, they are more prone to becoming sick or losing their bold hues. 

Similarly, having the right size enclosure will help to ensure they are active and able to interact with each other, making your enjoyment of the fish much higher. 

All in all, it really does make sense to opt for the often more expensive but wholly worth the price option of having a pond or aquatic fixture of the appropriate size installed to house your koi fish.

They are completely worth the extra expense and effort, especially if you want to truly enjoy their beauty, personality, and growth. 

You definitely will not regret upgrading their enclosure from a basic tank.