How Long Do Koi Fish Live?

How long do Koi fish live? Koi fish lives around 25 to 35 years long. Koi fish have a lifespan that is condition-dependent. While traditional Japanese Koi are said to live for roughly 40 years, the kinds outside of Japan may live to be as old as 15.

how long do koi fish live

About Koi Fish

Koi are among the hardiest freshwater fish that can be maintained in an aquarium. Having a koi fish as a pet is a big commitment, not because they’re difficult to care for but because they live longer than most other fish.

Name Koi Fish
Scientific Name Cyprinus Rubrofuscus
Life Span 35-40 years
Size 24 to 36 inches
Diet Omnivores
Tank Capacity 55 – 200 Galloons
Temperament Peaceful
Tank Setup Muddy bottomed freshwater environment

Ethical and Behavioural Considerations

Koi fish are docile and social creatures that thrive in groups of 5-15. Koi fish are only suitable for large ponds since they need much swimming space.

They are always searching for food and will use the whole tank.

Koi fish are notoriously dirty aquarium inhabitants because they like to burrow in the substrate between meals.

Koi fish will socialize with humans. They associate with food and maybe hand-fed after confidence has been established.

In colder climates, most koi fish species “hibernate” near the pond’s bottom, where they continue to swim and feed on algae.


Adult koi fish size varies widely among species. A koi fish will typically reach 24 to 36 inches at maturity.

Adult western domestic Koi will reach 12-15 inches, whereas Japanese Koi may reach a length of 22-26 inches. The maximum size of a jumbo koi is 34 to 36 inches.

Therefore, they are much bigger than the majority of aquarium fish. In addition to being simpler to care for than more giant tank fish species, they are also more affordable.


Over a hundred distinct koi fish species exist today, from rare, prehistoric breeds to hybrids of today’s most popular koi fish. Koi fish come in various colors, patterns, and shapes; nonetheless, their presence in any aquarium is undoubtedly captivating.

Koi fish utilize their maxillary barbels, two organs on either side of their mouths covered with taste buds, to take massive gulps of water and locate food in any environment.

The male koi fish is easily identified by its short, pointed, and opaque fins, whereas the female’s fins are more spherical and transparent.


Koi fish are omnivores with a broad diet range. Therefore they are pretty easy to care for in an aquarium. They devour anything before them, gobbling it down in huge mouthfuls.

In other words, what do you feed your koi fish?

Formulated with added nutrition, these pellets are perfect for Koi (with plenty of minerals, vitamins, and nutrients)

  • There was a lot of algae;

  • Larvae of insects;

  • Shrimp;

  • Lettuce;

  • Peas;

  • Watermelon;

  • Even human staples like rice and cereal.

Koi fish, even when fully grown, will not devour other fish despite their menacing appearance to smaller fish.

However, they will pick up fish eggs from the substrate or living plants in a tank.

Koi fish are notorious for uprooting aquarium plants due to their penchant for digging in the substrate. If you add weeds or give them responsibility for clearing away algae, they may stop caring for your plants.

Koi fish need to be fed three times a day, and you shouldn’t keep them with fish that they’d have to fight over food.


If you put in the effort and care necessary, breeding koi fish may be a lucrative enterprise.

Juvenile domestic koi fish are not too expensive to purchase, but setting up a tank properly may become pricey so you can breed Koi.

Follow these guidelines to maximize the success of a mating pair of koi fish.

  • For the month coming up to the mating season, provide a healthy diet for your koi breeding pair;

  • Following their natural life cycle, the best time to produce Koi is in the late spring and early summer (May and June);

  • When breeding Koi, it’s essential to start with robust adults since their offspring will inherit many of their traits;

  • Future koi parents should be between the ages of three and six when they mate;

  • At the ripe old age of 15, koi fish in captivity may successfully reproduce;

  • To successfully breed Koi in an aquarium, you must keep the Koi in a tank by themselves;

  • If you want your koi couple to be able to view their eggs after they’ve been laid readily, a spawning pad at the bottom of the tank is a good idea.

  • During spawning, maintain a water temperature in the aquarium of 65°F to 70°F;

  • During the “mating ritual,” male koi fish may seem to annoy the female, but he is helping her release eggs so he may fertilize them by pushing inside her.

  • Once the koi fry has hatched, a floating koi mesh cage/net may be used to protect them from predatory fish and the powerful filter necessary for a koi fish tank.

Fellow Tankers

Not because of disposition, but because they make much more of a mess than other aquarium fish, Koi may be challenging to maintain with others.

Constant digging at the substrate releases debris and muddies the water, making it difficult for delicate species to coexist.

Koi fish are generally docile and shy away from smaller fish, preferring to socialize with those of their kind.

Only fish species in which your Koi would have to compete for food and little fish of the Cyprinidae family, which might be scared and agitated by the great size of a mature koi, are incompatible with your koi fish.


Many elements outside the koi fish’s control affect its longevity; we’ll discuss them later. Stunning, dragon-like koi fish kinds are available, and keeping one as a pet for decades can pay off with a breathtaking show. In the same way, a house pet would respond positively to positive reinforcement from their owner via feeding; your koi fish will identify you as their owner and associate pleasant interactions with you with the anticipation of receiving food.

Goldfish Pond Lifespan

Goldfish have a potential lifespan of 5-25 years when kept in a pond. The average lifetime of a fancy goldfish in a pond is between 5 and 10 years. The average goldfish in a pond may expect to live between 10 and 25 years. The kind of goldfish, the pond’s condition, and the fish’s upkeep are all factors.

Once again, genetics have a significant role in the maximum lifespan of a goldfish in a pond. A higher quality of water is essential for fancier goldfish. The bred-for physical characteristic frequently turns out to be a liability. Rounder goldfish, for instance, have more excellent trouble swimming, floating, and maintaining bladder control because of their abnormal body shape.

Also essential is the water’s quality. Goldfish often have a longer lifespan in ponds with higher water quality, such as ecosystem ponds, just like with actual humans. The more improved and healthy our surroundings, the longer we may expect to live in them.

Factors That Determine the Koi Fish’s Lifespan

Several different variables may influence koi fish longevity.

Concentrations of Oxygen

Koi fish die suddenly from lack of oxygen more often than other stress.

Algae blooms are a vital contributor to oxygen depletion in koi ponds. As a byproduct of photosynthesis, oxygen is produced by algae throughout the day. When algae in Koi ponds grow uncontrollably, they consume as much oxygen as they release, killing the fish.

The abrupt depletion of algae in the Koi pond contributes to its low oxygen content. Algae may die of natural causes or by exposure to algaecide chemicals. When algae decompose, oxygen levels drop, which might be fatal for Koi.

There is no way to solve this issue without oxygen testing equipment.

In addition, waterfalls and fountains may be equipped with oxygen-supplying pumps and diffusers to keep pond oxygen levels stable. Putting up a Pond UV sterilizer is a good idea to avoid green water or massive algae blooms. Using a Söchting Oxydator is yet another efficient method of increasing oxygen levels.

pH Level

When a backyard pond’s pH is somewhere between 7.0 and 8.6, Koi fish flourish. Therefore, to keep the pond’s pH stable, you must get rid of damaged plants and stale Koi food. Water filtration devices are helpful in this regard.

Additionally, water additives help prevent pH-altering ammonia and nitrates from penetrating your pond’s water supply.


Regardless of how well-maintained your pond is, it won’t make up for poor genetics.

Japan is a world leader in the evolution of Koi. Koi breeders have worked hard to improve the gene pool, yet the Japanese variety still outlives its domestic counterparts.

Koi were exported from Japan, but the best of the breed stayed in Japan. Many best breeders start with imported Koi or fish from a solid genetic line. Great koi suppliers stock Japanese and American varieties and provide “what you see is what you get” selections. The cost of a koi will increase in proportion to the rarity of its breed.


Koi have a very short life expectancy regardless of how well they are fed.

One of the most critical factors in a Koi’s general health and development is the food they eat. Therefore, before giving your Koi anything, you should always do your homework and carefully read the labels.

Here are some qualities to look for in a complete Koi food.

  • Proteins like fish meal or soy Fats: 10% for juvenile Koi and 3% for adults

  • Carbohydrates such as those found in rose hips, soybeans, maize, and wheat

  • Vitamins and minerals including salt, potassium, calcium, and magnesium

Koi are known to appreciate orange peels, peas, rice, and shrimp in addition to the commercially available diet.

The close relationship between an owner and their Koi benefits the fish’s well-being. The Koi is a responsive, gregarious, and peaceful fish. That’s why it’s so important to get your hands dirty while feeding your Koi so you can develop a personal connection with them.

Talking to your Koi is a great way to pass the time. Take attention to how they respond to you as their caretaker when you feed them with your hands. The accomplishment justifies immense satisfaction.

Purity of Water

Providing your Koi with clean, fresh water is the most important thing you can do to ensure a long and healthy life. To prevent skin and bacterial problems in your Koi, the water in the pond should not include any chlorine, ammonia, nitrates, or nitrites.

You may maintain Water quality with periodic testing. When it comes to maintaining optimal water quality in the home, water test kits are invaluable.


Since Japan is often rather chilly during the winter, if the pond is winterized correctly, Koi may thrive.

During the colder months, koi fish go into hibernation. And this hibernating mechanism helps Koi live longer. This condition of hibernation, known as torpor in Koi fish, is triggered by temperatures of 50 degrees Fahrenheit or below.

Many inexperienced fish keepers either move their fish inside or insulate the outside pond to maintain the water temperature above 50 degrees Fahrenheit. It’s not a good idea to do that. Keep the water from freezing with a Pond De-Icer while your Koi spend the winter in hibernation for longer, healthier life.


The longevity of Koi is affected by the conditions in which they are housed. Generally speaking, you have three basic housing choices for your Koi.

Natural Ponds

Due to their size, Koi fish are often kept in outdoor ponds. The size and depth of an outdoor pond should be tailored to the needs of your Koi fish. The optimal Koi pond size is more than 1000 gallons and at least 3 feet deep. Koi are resilient fish, but they require a clean habitat well filtered biologically and mechanically. The health and happiness of your Koi depend on your attention to the pond’s water quality.

Home Aquariums

Having an indoor Koi pond may be a lovely addition to any room. But, please, respect the confines of the room. A larger pond is preferable.

Lighting, leakage, and humidity are essential variables to consider while caring for an indoor pond. Even while they appear great when brought inside (source), they need extensive preparation.


In aquariums, adult Koi seldom fare well. Therefore, it is not something I would ever suggest. However, you may keep young Koi successfully in an indoor tank.


Koi have a lifetime that varies with the food quality and cares it receives. Keep an eye on your garden ponds and provide them nutritious food as a good Koi keeper. Koi have been known to live for 30-40 years or more. Hanako, who lived almost 200 years old, is one of the few known outliers. Great love and care are essential to a happy, long-living Koi, regardless of age.

Frequently Asked Questions

Here are some FAQs related to Koi fish lifespan:

1. To what age do koi fish typically reach maturity?

What is the average lifespan of a koi fish? These fish have a lifespan of 20 years to more than 200 years. The typical lifespan is between 20 and 50 years.

2. How old is the oldest Koi in the world?

Hanako, a Koi fish from Japan, has a record for longevity among Koi. When she passed away in 1977, she lived for 226 years. Female scarlet fish were first spawned in Japan in 1751. An adult scarlet koi carp may live for up to 40 years in captivity.

3. When kept in a pond, how long do fish typically live?

In general, a goldfish’s lifespan is 10-25 years. Aged 5-10 years, fancy goldfish. If given the right conditions, goldfish kept in a backyard pond may survive for decades. As a species, humans have kept goldfish as pets for generations, but not necessarily in ways that promote their long lives.

4. What’s the going rate for Koi?

Koi fish prices vary from store to store and even from one fish to the next. Depending on the kind, their fees range from $20 to $85 per.

5. When kept in a pond, how long do Koi typically survive?

Koi have a potential lifespan of over a century, while the average is closer to 30 years with proper care. Because fish continue to develop throughout their lifespan, the highest prices are paid for the oldest, largest, and most attractive specimens. Koi need ample space, which may add considerable expense to the upkeep of your aquarium.

6. Do koi remember who their caretakers are?

Dog-like in their devotion, emotions, and memory, most Koi owners can attest that their fish have all three. Koi have the same senses as humans and are also endowed with long-term memory. Try it at home; Koi aren’t only good at remembering names and excellent at memorizing faces.

7. How long do koi fish last without eating?

To put it briefly, Koi fish can go without food for up to two weeks. There are several reasons why Koi may go without food for so long. The two-week estimate is derived from the koi fish’s metabolic rate at the peak of summer when it feeds on a near-constant basis.

8. What shouldn’t you feed your koi fish?

Koi fish should not be fed foods that are heavy in carbs. Avoid giving them white bread, peas, and maize as well. Koi fish have trouble metabolizing carbohydrates. It would help if you didn’t provide them with anything you’ve caught in the wild.

9. How frequently do I need to feed my Koi?

How Often Should Koi Fish Be Fed? Once a day is the minimum amount of food your fish needs. There will be enough food for the fish for the pond to thrive. Overfeeding may lead to algal growth because too many nutrients are released into the pond.

10. Are Koi able to digest their kind?

Although Koi aren’t often thought of as predatory, they are, in fact, opportunistic feeders who will consume anything in their environment that meets their nutritional needs. This implies that other fish, even their own young, may end up on their menu.


Incredible as it may seem that some koi fish may outlive their owners and reach their 50th birthday being kept as pets, the responsibility of caring for a koi fish is much higher. To ensure your koi fish lives to its full potential, you must provide it with suitable habitat and nutritious food. Beautiful and massive, koi fish are among the most low-maintenance aquarium inhabitants.

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