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How long do Koi Fish live?
If you’re a new Koi keeper who wants to buy Koi for your garden pond because it has a life expectancy of around 100+ years, you may be in for a surprise!
Contrary to belief, the life expectancy of Koi fish depends on keeper to keeper. So, there’s no one answer to, “How long do Koi live?”. I’ll explain.
Koi fish, on average, will fall under 3 ranges of lifespans:
- Koi kept in ideal conditions; with optimum water quality, pH levels, nutritional status, and low stress, can live up to their 50s, 60s, and even 90s. There are some outliers, like Hanako, who reportedly lived to 226 years!
- Koi fish kept with novice fish keeping skills live much shorter. For instance, 3-5 years, because the owners may struggle with essential knowledge in the hobby. As a result, these Koi have reduced lifespans.
- For most Koi collectors, Koi fish are more likely to live above 25 years. You might be wondering about the huge difference, as that is still short. That’s because most of the Koi outlive their owners and depend on others for ideal conditions and care. Eventually, people lose discipline on their pond maintenance, which might end up shortening the lifespan or killing the fish.
Concerning the above points, the life expectancy of Koi fish varies from condition to condition. However, the breeds outside of Japan can reach up to 15 years of age, while the lifespan of traditional Japanese Koi is estimated to be around 40 years.
The 7 Factors That Affect The Lifespan of Koi fish
There are various factors that affect the life expectancy of Koi fish.
- Oxygen levels
- pH level
- Water quality
1. Oxygen Levels
Lack of oxygen is the most prominent stressor that leads to the sudden death of Koi fish.
One major factor that adds to the loss of Oxygen in Koi ponds is algae blooms. Algae produce oxygen in the daytime as a by-product of photosynthesis. If algae are growing out of control in Koi ponds, they take in Oxygen as they produce, causing the fish to die.
Another factor that affects the oxygen levels in the Koi pond is the sudden loss of algae. The algae can die as a result of a natural death or any algaecide chemical. When the algae die, the oxygen depletes, which can result in Koi death.
The only solution to this problem is the testing devices that accurately read oxygen levels.
Furthermore, to maintain oxygen levels, install pumps and diffusers that bubble the air into the waterfalls or fountains to provide adequate oxygen to the pond. To prevent large algae blooms or green water, consider adding a Pond UV sterilizer. Another effective way to increase oxygen is the use of an Söchting Oxydator.
2. pH Level
The Koi fish thrive in garden ponds with a pH level between 7.0 and 8.6. Therefore, you should remove all decaying vegetation and leftover Koi food to maintain the pond’s pH levels. To help with this, water filtration systems come in handy.
Moreover, water additives help block ammonia and nitrates from entering your pond that might alter the pH levels.
No matter how optimal your pond conditions are, nothing beats genetics.
Japan is at the forefront of Koi development. And even though the Koi breeders have tried their best to enhance the gene pool, the Japanese Koi has a greater lifespan than the domestic Koi.
When the Koi were introduced to other countries outside Japan, the highest quality Japanese Koi did not leave its place to maintain the legacy. Many of the top breeders work with imported Koi or worked with a great genetic line and breed from there. A great Koi seller will provide a what you see is what you get selection, and will have a mix of imported Japanese Koi and domestic koi to select. The more premium breed the koi is, the more expensive it will be.
The lifespan of Koi greatly depends on its nutritional status.
It is observed that the best Koi food plays a vital role in Koi’s overall health and growth. Therefore, you should always do your research and read the labels thoroughly before feeding your Koi.
Here’s what you should look for in a balanced Koi Food.
- Proteins, such as fish meal or soy
- Fats: 10% for young Koi and 3% for adult Koi
- Carbohydrates, including rose hips, soybeans, corn, wheat
- Vitamins and minerals, such as Calcium, magnesium, sodium, etc
Besides store-bought food, Koi enjoy orange peels, peas, rice, and shrimp.
One thing that adds to a healthy Koi lifestyle is the bonding with its owner. Koi are social, docile animals that respond really well. Therefore, feeding time is a great opportunity to bond with your Koi and feed them with your hands. It’s always fun to interact with your Koi. Feed them with your hands, and notice the way they recognize you as their rearer. It is something to be truly proud of!
5. Water Quality
If you want your Koi to live longer and happier, the best thing you could provide them with is quality water. The pond water should be free of chlorine, ammonia, nitrates, and nitrites to ensure maximum protection and safety for your Koi against skin / bacterial diseases.
You can maintain the water quality with regular testing. Home Water Test Kits are excellent to keep water quality at its best.
Since Koi originate from Japan, they are cold-water fish that can survive in extreme temperatures, provided with proper pond winter preparation.
Koi fish hibernate during the winter season. And this process of hibernation contributes to a longer lifespan of Koi. The hibernation occurs at temperatures at or below 50 °F, and in Koi fish, the state of hibernation is referred to as torpor.
Many novice keepers bring their fish inside or insulate the outdoor pond to above 50° F. This is not recommended. To make your Koi live longer and happier, you should allow it to hibernate during winters, and only keep the water from freezing during their hibernation by using a Pond De-Icer.
The environment in which Koi is kept affects their lifespan. Mostly there are three options for your Koi to live in.
Most people prefer to keep their Koi fish in outdoor ponds due to their size. For outdoor ponds, the depth and size should fit your Koi’s requirements. The ideal size for the Koi pond should be over 1000 gallons and at least 3 feet deep. Also, while Koi are hardy animals, they need a proper environment with biological and mechanical filtration. Pond water maintenance is imperative to keep your Koi healthy and happy.
Indoor Koi ponds are a beautiful addition to your home interiors. However, be mindful of the space. The bigger the pond, the better.
Some other factors need your proper consideration, including the lighting, leaks, and humidity to maintain your indoor pond. They look amazing indoors (source), but lots of planning is required.
Mature Koi never do well in aquariums. Therefore, I would never recommend it. However, you can keep young Koi indoors in an aquarium.
What is the oldest type?
The oldest Koi fish ever, to date goes by the name of Hanako.
Hanako was a female Koi fish that was scarlet-colored. The interesting part is, on average, the lifespan of Scarlet Koi is around 40 years. However, Hanako weighed 7.5 kg and aged 226 years old in the 1970s.
Dr. Komei Koshihara, Hanako’s last owner, got her age verified by professor Masayoshi Hiro, who extracted two scales of Hanako to determine her real age.
Dr. Komei Koshihara claimed that Hanako and he were the dearest friends that shared a beautiful bond together.
On a radio show in 1966, Dr. Komei Koshihara said, “When I call her (Hanako) saying ‘Hanako! Hanako!’ from the brink of the pond, she unhesitatingly comes swimming to my feet. If I lightly pat her on the head, she looks quite delighted. Sometimes I go so far as to take her out of the water and embrace her.”
Dr. Komei Koshihara was an avid Koi keeper who explained to us the right way to calculate the age of Koi. He said, “Just like a tree had its annual rings on its trunk, a fish has its annual rings on its scales. One just has to count them to know the age of the fish.”
Hanako was passed on to generations in the Koshihara family. After 2 centuries, 2 decades, and 6 long years, Hanako died on 7th July 1977, in Japan.
How long do they live in captivity?
The average lifespan of Koi fish in captivity is 25-35 years.
Whereas in the wild, they are known to be living for 15 to 20 years, and male Koi live longer than females. Japanese Koi tend to live longer due their superior genetics.
Do they die of old age?
I haven’t come across any Koi that died of old age. In fact, it’s the water conditions and the diseases that make your Koi so vulnerable to life-threatening complications.
According to NCBI, age is not a disease. Although, a common cause of all age-related diseases. Therefore, I don’t believe Koi die of old age.
How old is a 2-inch koi-fish?
A 4-5 inch of Koi fish should be around 1 year old. Similarly, a 2-inch Koi fish should be in its first summer age, i.e., 0.
How Long Will My Pet Live?
The answer to this question depends on the aforementioned factors; health, feeding, water temperature, and water quality. Koi keeps on growing and living until it has reached its genetic age and size. On average, Koi can live up to 20, 30, or even 60 years.
The lifespan of Koi depends on what you feed it and how you keep it. Therefore, as a responsible Koi owner, you should always keep a track of your garden pools and feed food high in nutrition.
Koi can live up to 30-40 years and longer. Some are rare exceptions, such as Hanako that lived for over 200 years. Whatever the age may be, great love and care are the keys to a happy, long-living Koi.
Do you have a Koi that has lived through multiple generations of your family? If so, share below. It’s always amazing to hear about Koi that have lived for many years.
Mark is the founder of Aquarium Store Depot. He started in the aquarium hobby at the age of 11 and along the way worked at local fish stores. He has kept freshwater tanks, ponds, and reef tanks for over 25 years. His site was created to share his knowledge and unique teaching style on a larger scale. He has worked on making aquarium and pond keeping approachable. Mark has been featured in two books about aquarium keeping – both best sellers on Amazon. Each year, he continues to help his readers and clients with knowledge, professional builds, and troubleshooting.