Yes koi fish can live in tanks and aquariums quite happily providing you have a well filtered and aerated tank that is big enough to handle them.
How much space you have available is the number one factor to take into consideration.
Koi need a lot of water so you will need to have a space in your home or office for a very large tank.
Really big! At least 250 gallons at a minimum per koi!
Adult Koi require 250 gallons each so even if you intend to only keep three to five koi you will need a very large tank.
As a rough guide koi can grow at eight inches per year and will grow quickest in the first three years.
Growth rates after this will then tend to taper off.
They reach maturity at roughly ten years and can be quite large at that stage assuming they have the space to grow.
Under ideal conditions koi can live for roughly 50 years so they are a long term commitment and you really need to be able to commit to these fish to give them the best possible life.
They will however rarely live to such a ripe age in an indoor fish tank.
While four or five juvenile koi may be perfectly happy in a large tank, once they grow to adult size you will have to make a decision at some point.
Upgrade your tank size or transfer them to a pond.
Most people will not have the space for large adults in an indoor tank so it is just not practical to think of a tank or aquarium as a long term home for them.
The decision to keep koi in a tank should not be taken lightly so please consider the space requirements and how long they live before you dive in head first.
If you can care for them in the correct manner then koi can make wonderful pets and over time will learn to recognize you as their keeper.
They will even eat from your hand once they have learned to trust you.
Ultimately a purpose built koi pond is the best place to keep your koi healthy and happy.
Koi Fish Tanks
1. Koi Fish Minimum Tank Size
The size of your koi aquarium should be big enough for their first three years at a minimum.
As mentioned above koi growth rates in the first three years will be at the highest, then they gradually taper off over time.
Indoor koi fish tanks can make a great looking center piece of any room but it needs to be a position that does not distress the koi, preferably with one side against a wall on not in direct sunlight.
Koi in aquariums will never reach the size that fish kept in a large well kept and maintained koi pond will.
2. Shape and Design
Most large aquariums will be rectangular in shape and there is good reason for this.
A perfectly square tank will not be as well aerated or filtered as a rectangular one.
A long shape allows for consistent flow flow of water in two directions. In a square tank each corner will create a dead space of much calmer water.
Rectangular ones allow a long distance for the water to flow in one direction which is also much healthier for the koi as they have a two directional flow of currents that they can swim against.
In a square tank the water will effectively flow in a circle around the tank with the water in the middle and the corners being much slower which is less than ideal.
You will also need a tank that has a cover as koi fish do jump out of water and the only way to stop them from jumping out of your tank is with a proper well tied down cover or lid on the tank.
3. Koi Fish Aquarium Filtration
Koi eat a lot of food and as a result will produce a lot of waste so you will need to have filtration system that can handle this.
In-tank filters are fine for smaller species in average size aquariums but for a large koi tank with several big fish you will may well need a much more powerful external filtration system.
This will of course increase the cost of keeping koi in an aquarium and will also require a bit more space.
Koi need clean water, and a subpar filtration system will ultimately result in them dying from some form of disease.
4. Koi Fish Tank Aeration
Just like clean water, koi also require well oxygenated water so a quality aquarium air pump is a must.
What Fish Can Live with Koi in a Tank?
Just be aware that large koi do eat other fish so if you are planning on keeping them in a tank with other fish bare this in mind.
If you are mixing koi and goldfish make sure that the goldfish are as big as possible.