Bright orange koi fish visible under the surface of a pond.

An avid backyard pond owner knows that koi fish make for an attractive and peaceful addition to any body of water. Adding koi fish to your backyard pond is a great way to add color and life to your water feature.

But how long do koi fish live in a backyard pond? How do you care for them, so they live long, happy lives?

In this blog post, we’ll answer these questions and provide tips on caring for your koi fish.

How Long Do Koi Fish Live On Average?

On average, a koi fish’s lifespan ranges from 25 to 30 years. The key to a long life for your koi fish is to provide them with a healthy environment. This means a pond with clean water, lots of plants, and plenty of room to swim. Koi are also very resilient fish. So even if you live in an area with cold winters, your koi will likely survive–as long as you take steps to protect their pond from freezing.

You may also want to know how long goldfish can live in an outdoor pond.

Male Koi Fish vs. Female Koi Fish

Males tend to live slightly longer than females. The main reason male koi live longer than female koi is that they don’t get pregnant. Pregnancy takes a lot out of a koi fish; as a result, females tend to age more quickly than males. In the wild, it’s not uncommon for female koi to die soon after giving birth.

Male koi are also less likely to be eaten by predators. Predators often target female koi because they are easier to catch when carrying eggs. On the other hand, male koi are typically left alone by predators since they don’t have anything that makes them an easy target.

Japanese Koi Fish vs. Domestic Koi Fish

The answer to ‘how long do koi fish live’ differs between Japanese and domestic versions.

Domestic koi fish tend to live for about 15 years on average. This is much less than Japanese koi. Japanese koi fish have a longer average lifespan of 40 years. Some can even live well into their 60s!

Here are the main reasons why the difference is so huge:

Breeding Conditions

One of the primary reasons why Japanese koi fish live so long is because they are bred in ideal conditions. In Japan, koi breeders take great care to produce healthy offspring. They use only the strongest and healthiest fish for breeding purposes, and they raise the fry in well-maintained ponds with clean water.

As a result, Japanese koi are much hardier than domestic koi since domestic koi are often raised in less-than-ideal conditions.


Another factor that contributes to the longevity of Japanese koi is the diet that these fish are fed. In Japan, koi breeders have access to high-quality food designed explicitly for koi. This diet is packed with nutrients that help keep koi healthy and robust.

On the other hand, domestic koi are often fed lower-quality food that is not as nutritionally dense. Over time, this diet difference can significantly impact a koi’s health and lifespan.

Pond Size

Finally, Japanese koi benefit from being kept in large ponds with plenty of space to swim around. This allows them to exercise their muscles and stay active.

Domestic koi are often kept in smaller ponds or tanks, leading to a sedentary lifestyle and increased health problems over time.

But, these numbers are nothing compared to the oldest koi fish on record.

The Oldest Koi Fish

Of course, 25 to 30 years is just the average koi lifespan. Some individual koi have been known to live for over 200 years! The oldest koi fish on record was Hanako, a Japanese koi fish born in 1751 and died in 1977 at the ripe old age of 226.

How To Estimate Koi Fish Life Expectancy

Koi fish swimming in a pond at night, lit up with underwater light features.

It’s hard to estimate how long koi fish live. If you properly care for them and their environment, you can count on them living longer.

One aspect that will better determine how long they live is which variety of koi fish you own. For example, due to their delicate nature, Nonaka Kohaku koi fish have shorter lifespans than other varieties. On the other hand, Kikokuryu koi fish can live for upwards of 100 years thanks to their hardiness.

5 Main Factors That Affect How Long Koi Fish Live

Several factors influence the answer to ‘how long do koi fish live.’ Here are the primary 5 factors:

1. Size Of The Pond

In general, the larger the pond, the longer your koi fish will live. That’s because larger ponds provide more room for koi fish to swim and explore and offer more stable water conditions. If you have a small pond, your koi fish may only live 5 to 7 years. But if you have a large pond, they could easily live 15 years or more.

2. Quality Of The Water

The quality of your pond water also dramatically impacts how long your koi fish will live. Koi fish are susceptible to changes in water quality, so it’s essential to keep an eye on things like pH levels, temperature, and dissolved oxygen content.

3. Type of Food

What you feed your koi fish can also affect their lifespan. It’s essential to choose a high-quality food designed specifically for koi fish. Pellets are generally a good option since they provide all the nutrients your koi fish needs in one easy-to-eat package.

You can feed them certain human foods, but do your research first.

4. Genetics

Genetics also plays a role in determining how long koi fish will live (just like with humans!) Some strains of koi fish are known for being hardy and long-lived, while others are prone to disease and have shorter lifespans.

When choosing koi fish for your pond, be sure to research the different strains to select ones known for being hardy and long-lived. If you want to learn more about the different types, be sure to check out our guide to 11 types of koi fish.

5 . Husbandry Practices

Finally, how you care for your koi fish can also affect how long they live. Things like improper feeding, inadequate filtration, overstocking, and poor water quality can all lead to stress and illness in koi. This can shorten their lifespan. Conversely, good husbandry practices like providing a clean and spacious home, feeding a balanced diet, maintaining good water quality, etc., will help ensure a long and healthy life.

How To Extend The Lifespan Of A Koi Fish

Two multi-colored koi fish swimming near each other.

If you want the answer to ‘how long do koi fish live’ to be longer, it’s crucial to provide them with proper care. Here are a few tips:

Give Them A Large Pond

Koi grow quickly and can reach lengths of up to 3 feet within a few years. They need plenty of room to swim and grow, so make sure your pond is at least 10 feet in diameter.

Keep The Water Clean

Koi are very sensitive to changes in water quality, so it’s essential to keep the pond clean. Perform regular water tests and take steps to correct any problems as soon as possible.

Feed Them Well

Koi are omnivores, so they need a diet that includes plant and animal matter. Many commercial foods available will provide your koi with the nutrients they need.

Protect Them From Predators

Koi are a favorite food of herons, raccoons, and other animals. There are many ways to protect pond fish from predators.

Take Them To The Vet

Just like any other pet, koi need to see the vet regularly. Your vet can help you ensure your fish are healthy and identify any problems early on.

What Impacts The Health Of Koi Fish

Colorful decorative koi fish float in an artificial pond, view from above.

Several factors can impact the answer to ‘how long do koi fish live’.


Koi fish are cold-blooded animals, meaning their internal body temperature is directly impacted by the temperature of their environment. Koi fish generally do best in water between 55 and 75 degrees Fahrenheit.

Too cold water can cause metabolic problems and make koi fish more susceptible to disease. Water that is too warm can lead to stress and overheating.

Koi fish can survive if the surface of the water is frozen. They enter a hibernation-like state and float near the bottom of the pond.


Koi fish need access to dissolved oxygen in the water to breathe correctly. A few different factors can impact the amount of dissolved oxygen in your pond. These include the depth of the water, the surface area of the water, and the amount of vegetation present.

You can increase dissolved oxygen levels by adding an aerator or simply by ensuring that your pond is adequately stocked with plants.

Water Quality

The quality of your pond water has a direct impact on the health of your koi fish. Maintaining proper pH levels is especially important; koi prefer slightly alkaline water (between 7 and 8).

You should test your pond water regularly using a pond water testing kit. This will help you identify any potential problems early on to address them efficiently.

Solve Your Pond Problems Using Gradex Construction

Along with knowing the answer to ‘how long do koi fish live’, Gradex also knows more about backyard ponds. If your pond isn’t a suitable environment for koi fish, fill out our contact form today! We can help build a pond ideal for your future (or current) koi fish.