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How Long Do Koi Fish Live? Average Lifespan, Data & Care

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By Lindsey Stanton

koi fish in aquarium

We all want our fish to live as long as possible. Koi are widely kept as ornamental pets that should be housed in ponds or water gardens. They are brightly colored and can grow to large sizes. The koi is well-known for its long lifespan, and they have been documented to live between 20 to 30 years. This is another reason they make such popular pet fish in the aquarium industry.

Koi fish are closely related to goldfish who are known to have a similarly long lifespan. Both are descendants of wild carp and have been selectively bred through the centuries to produce stunning colors and patterns.

In this article, we will provide you with all the information you should know about the lifespan of koi and how you can ensure that they live till old age.

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How Long Do Koi Fish Live?

If you are new to owning koi, you may be surprised by how long they can live. Not only are these hardy fish that are tolerant to a lot of diseases and conditions, but they also live very long. The average koi fish typically reaches between 20 to 30 years of age. The overall lifespan depends on the keeper, their level of experience, and how well-cared-for the koi is. Koi are not difficult to keep healthy if their conditions are right, but not many owners will get it to ideal levels for the first few years.

koi fish in fresh water aquarium
Image Credit: Arunee Rodloy, Shutterstock

Minimum Lifespan

If koi are kept in poor conditions by an owner with novice skills, they are not going to live if is expected. This is due to the care they receive. Properly cared for koi will always live longer unless there is a health issue or genetic factor that plays a role.

Novice owners generally do not know how to properly care for these fish, which is understandable since they are only starting in the aquarium hobby. They may not be able to keep the koi in a fully cycled pond with the right water quality and dissolved solid levels.

Koi that are subjected to poor conditions will live to around 10 years of age. This may seem like a long time in comparison to other fish, but it is quite short for koi fish, and they have only just begun to reach adulthood.

Maximum Lifespan

Koi have a varying maximum lifespan. If they are kept in optimal water conditions, the Japanese koi can live between 35 to 40 years. It is not uncommon for them to live till the ripe old age of 50 years. The nutritional status should be good, along with the correct water quality, and pH levels.

There are different types of koi, which may have slightly altered lifespans.
  • Butterfly koi – 25 to 30 years
  • Tancho koi – 20 to 28 years
  • Koromo – 25 to 30 years
  • Showa – 20 to 30 years
  • Kohaku – 25 to 30 years
  • Taisho sanshoku – 20 to 28 years

Oldest Koi on Record

One of the oldest koi on record is Hanako. She was a female koi with a scarlet coloration who lived to a whopping 226 years of age! She weighed in at 7.5 kg and is considered a Japanese koi who have a maximum lifespan of 40 years. Her age was verified through her last owner who had her scales tested in a laboratory. Hanako had become attached to all her owners and even let them pat her head. She would come when her name was called, and she survived through generations of different owners who provided her with proper conditions. She belonged to the Koshihara family, and after being handed down many times, she sadly passed away in 1977.

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The 8 Factors That Affect the Lifespan of Koi

These are the main reasons that your koi may not be reaching its full lifespan potential:

1. Pond size

The larger the pond, the better. Koi grow huge and need adequate swim space to be content. A trio of koi should be in no less than 400 gallons of water. This should be able to house them their entire lives. If you plan to add larger groups of koi to the pond, it should be increased by 50 gallons per new addition. Larger ponds also help lower the toxicity of waste build-up in the water and effectively dilutes it. Small tanks can cause the koi to feel stressed, which will lower their immunity and increase the likelihood of the koi falling ill and dying.

koi fish pond
Image Credit: Yedidia Klein, Pixabay

2. Water quality

The pond should be fully cycled before you add in koi. There should also be a filter or two to allow beneficial bacteria to establish. This will help keep the levels of ammonia, nitrites, and nitrate in the water which are toxic to fish within ideal levels. In some cases, you may need to refill the pond every week during the summer months as the water evaporates faster. This adds in more clean water which will help to dilute the toxins. A poorly maintained pond can result in a shortened lifespan.

3. Oxygen

Koi require a lot of oxygen. Most pond filters have large bubblers attached that help increase surface agitation. There are also pond waterfalls that can be installed to help increase surface movement and allow more oxygen to enter the pond. Koi will suffocate without large amounts of oxygen in the water.

Koi Carp
Image Credit: Mikro Graul, Shutterstock

4. Wintering

Koi that do not go through a proper wintering stage are less likely to reach old age. Harsh winters can cause the pond to freeze over or even become too cold and cause your koi to become ill. Adding in a 200W heater on either side of the pond can help combat this problem.

5. Environment

The environment plays a big role in the lifespan of your koi. These fish can fall prey to other animals like dogs, cats, birds, and wildlife. The pond should be secured with light netting to prevent other animals from having access to the koi. The pond should be shaded with a few hours of light sunlight hitting the water during the day. If the pond is kept in full sunlight, the water may become too warm for the koi to feel comfortable.

beautiful koi fish
Image Credit: IamSuperPear, Shutterstock

6. pH levels

This is an important factor that applies to water quality. The pH should be kept within a range between 6.5 to 7.8 on the pH scale.

7. Diet

Getting the diet right is crucial to the longevity of your koi. Koi should be fed a diet that consists of a high-quality commercial pellet, live foods like blood worms, insects, and their larvae. This will ensure that they are kept healthy. An inadequate diet will eventually affect their health and cause them to live short lives.

koi fish eating pellets
Image Credit: Russell De Boer, Pixabay

8. Genetics

The genetic history of koi fish is going to determine their lifespan. Quality-bred koi fish will live longer because they were bred to have a strong immune system and minimal health issues. Whereas poorly bred koi are more prone to illness, deformities, and a short lifespan.

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Koi Inheritance

Koi are known to outlive their owners. You should have them written into your will and allocated to the next owner if you were to pass away. The next person to inherit the koi should be told how to take care of them properly or should have previous knowledge on how to care for them. This is the most beneficial way to get your koi to live for a long time.

Final Thoughts

Koi have an interesting lifespan, and you are unable to determine how long your koi fish will live. Time will eventually provide the answers and you will begin the notice if your koi is showing signs of old age which will indicate how long the koi has left to live. If you provide your koi with the right conditions and diet, you should expect to have them around for the next couple of decades.

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