If you are a koi owner and breeder like myself, a common question we are asked often is how long do koi fish live. Well, in this primer, I’ll provide an answer and some other helpful information touching on the lifespan of koi.
Table of Contents
How Long Do Koi Fish Live?
Koi fish live for 25 – 35 years, on average. Some will live considerably shorter and others longer. There are many factors that determine the lifespan of a koi such as the location, food, environment, and type of koi.
Factors that determine the lifespan of koi include:
- Genetics
- Nutrition
- Water quality and environment
- Wintering
Koi Lifespan Table
| Number of Years | Situation or Location |
| The average lifespan of koi in captivity is 70 years. | In captivity or the wild |
| The average lifespan of koi in a tank is 50 years. | In a tank |
| The typical lifespan of koi in a pond is 20 – 40 years. | In a pond |
| In summer – 2 weeks. During this season, they take tiny amounts of foods from sources such as algae, and bugs. They can survive the entire winter without food. Avoid feeding them if the water temperature is over 52 degrees. | Without food |
| Without oxygen, the lifespan of koi is 2 days on average. | Without oxygen |
| Koi can live without water for 3 – 4 minutes, on average. | Out of water |
| On average, koi can live without a filter for 2 days. | Without a filter |
| koi can survive the entire winter. | In the winter |
| Koi can live inside a bag for 7 – 9 hours. | In a bag |
How Long Can a Japanese Koi Fish Live?
The lifespan of the Japanese koi breed is 40 years. Genetics or breeding is the major factor that informs the huge difference in the life of Japanese and ‘domestic’ koi.
Factors That Determine the Lifespan of Koi
Having aforementioned some of the factors that determine the lifespan of koi, now let us look at them in detail, individually:
Genetics
Genetics plays such a big role in the life of your koi. Excellent genetics form the basis of their good health that is necessary to ensure they prosper and live long.
Koi, whose origin is at the foot of Japan mountains, are from three strains of the common carp. In the early days, Japanese koi breeders started to selectively breed the koi generations.
You can trace their breeding to as far as 1820.
One of the things you must give it up to the Japanese breeders is their success in the trade. In addition to that, they also boast strict culling methods as well as water quality which the fish thrive in.
Because of this, they produce nothing short of healthy fish. Moreover, because of the longer period that they have been breeding fish, it means that their pool of genes is stronger compared to others.
In the United States, breeding of koi started roughly 100 years ago. Although American breeders produce genetically excellent koi, the truth is that they are yet to perfect the art.
Because of this fact, American koi lives shorter compared to their Japanese counterparts.
The American koi breed is generally larger. However, the methods utilized in bringing them up and grow might shorten their general life span.
Although the breeding of koi has been taking place for centuries, new varieties continue being produced throughout the world today.
When in the market for koi, ensure you reduce their time as much as you can. If possible, shop locally.
When ordering online, choose the fastest shipping method. The main reason for outlining this fact is that travel can cause stress and in severe instances, death regardless of how strong the fish genetics might be.
Nutrition
A well-balanced diet is paramount for maintaining colorful and healthy koi. What you feed your koi plays a big role in affecting his or her healthy and lifespan indirectly and directly.
The quantity and quality of food served to affect your koi in terms of slugging behavior, weakened immune system, and general health all of which affect its life.
In addition to reduced lifespan, poor nutrition also results in less attractive fish. The colors of your koi will look pale.
Overfeeding the little one also harms his or her life. The uneaten food builds up at the pond’s bottom or inside the filtration system which results in the poor quality of water.
As a result, poor water quality not only causes stress to the fish but also harms their health and reduces their lifespan.
The rule of thumb is to avoid feeding your fish more than they can handle in five minutes.
The good thing is that a huge selection of commercially available food for koi. Granules, flakes, chunks, and pellets are some of the most popular ones.
Such food is not only effortless to feed but also to store. You can also choose for specific needs such as season, color, water temperatures, and growth.
Common ingredients present in commercial koi food include blood meal, wheat flour, wheat germ, anchovy mean, shrimp meal, and whitefish meal.
It is also possible to supplement your koi’s food with live insects which they tend to love. Some of the common insects you can feed koi include mosquito larvae, white worms, and crickets.
When feeding insects to koi, you must be cautious as some might have a disease or stingers.
Feed your koi the following food categories to improve their health and increase their lifespan:
- Fats – While adults need 3% of fats in their diet, young ones require 10%.
- Protein – Protein can be either soy or fish meal.
- Carbohydrates – Look for wheat, corn, soybeans, and hips in the maiden five ingredients.
- Mineral and vitamins – Koi need sodium, potassium, magnesium, phosphorus, and calcium.
As you feed your koi, make sure that there is enough oxygen in the pond as it affects their digestive ability. Before you feed them, ensure the weather is friendly.
Rain decreases oxygen in the water which has an impact on digestion.
The other thing that affects oxygen in water is your pump. For this reason, inspect your pump frequently to establish whether it is working optimally or it needs repair.
If it is down, avoid feeding your koi as they can die.
Finally, yet importantly, consider adding some plants to the pond as they provide the necessary or desired oxygen.
Environment and Water Quality
The environment and quality of the water a koi lives in is important to a long lifespan of a koi.
Water Quality
The quality of water your koi live in is a SIGNIFICANT factor in their lifespan. Poor quality water not only causes stress but also makes koi susceptible to diseases.
These two issues harm their lifespan.
Some of the water quality you need to monitor carefully are:
PH
Hydrogen ions determine pH levels. High levels create more toxic forms of Ammonia thus making it essential for frequent water testing.
Fortunately, if you are a new fish keeper, just know that koi boast the ability to tolerate an array of pH levels compared to other fish.
Ammonia
Some of the causes of ammonia include rotting food/plants, deceased fish, and fish waste. Ammonia weakens the immune system of your fish.
On top of that, it can also stress them.
Of great importance to note is that ammonia accumulates in real-time because of overcrowded ponds and overfeeding.
Just like you have already learned on this primer, it is wise to refrain from offering additional food or overstocking your pond with koi.
If your koi breed, the prudent thing to do is search for homes for their fry. Doing this prevents overcrowding.
Chlorine
Chances are high that your water contains chlorine if it is from a well or tap.
Interesting Fact: Koi cannot live in a tap or well water laced with chlorine. Chlorine will kill them.
As you set up your pond and add some water, make sure you get rid of all the chlorine through treatment.
Nitrites
Nitrites, just like Ammonia, are a major contributor to the growth of algae. Plants are handy at maintaining appropriate nitrite levels inside the pond.
Does your pond have frequent algae blooms? If yes, then you need to test its nitrite levels.
Maintaining appropriate levels of these factors is possible with regular testing. This home water test kit can be handy when it comes to testing.
Alternatively, you can take some water samples to a nearby aquarium store to have it tested.
Environment
Environment, just like water, is crucial to the healthy lifespan of your koi. This factor can either extend or shorten the life of koi.
Regarding the environment, here are the three main options you need to be considerate of:
Outdoor Ponds
Many koi owners prefer to keep their fish in their outdoor ponds because of size. If you are one of them, you need to consider these factors when setting up your pond:
- Bigger is always better – The bigger the size of your pond, the less stressful it will be for your koi to grow.
- Sunlight – Although some sunlight is necessary for your outdoor pond, too much of it not encourage algae growth, it also causes your koi to overheat.
- Depth – The recommended depth of koi ponds is not less than 5 feet deep. Before you dig, establish the sections where power lines are buried.
- Predators – Thoroughly protect your outdoor pond against fish predators.
Indoor Ponds
Indoors ponds are a darling of many koi owners. Consider these factors before setting up yours:
- Weight – Due to the heavy nature of water, ensure you reinforce the floor in such a way that it bears the weight and prevents slippage which can cut the life of koi instantly.
- Lighting – Natural lighting is friendly to koi. Although underwater lighting can be appealing to us owners, avoid keeping them on for long as they can come in the way of your fish sleeping.
- Drainage – At some point, you will have to drain water. Put this into consideration during the design phase.
- Leaks – When coming up with an indoor pond, ensure you seal all sections that can cause leaks.
- Humidity – Indoor ponds add humidity indoors. Fortunately, you can manage this aspect with fans.
Aquarium
Although you can raise your koi in an aquarium, experts do not advocate for it.
Their life is best suited in a pond. If you intend to go the aquarium route, ensure you set up a large one that features a secure lid because of their size.
In addition to that, ensure they boast an aggressive filtration system that manages their waste.
Wintering
Temperatures in some regions of the world in the winter are extremely harsh. While that is the case, with proper care, your koi can survive even these harsh, cold conditions.
What they do in winter is to hibernate. By allowing yours to do so, you can extend their lifespan.
Some koi owners choose to install a heater inside the pond.
Doing this keeps them warm during the cold season. However, if you opt to do this, note that they will not hibernate.
Lack of hibernation in winter reduces their lifespan although it might seem like the most humane thing to do.
The prudent thing to do in winter is to allow your fish to hibernate.
Why Do Koi Fish Live So Long?
Hibernation is the chief reason koi live so long.
Another reason is the cold environment. The fact that it was raised in a cold environment is perhaps one of the major reasons that the longest living koi managed to click 226 years.
Other reasons for their long lifespan have been discussed on this primer.
How to Determine Koi’s Age?
You can determine the age of koi in various ways.
The first one is by measuring their length and then verifying the measurement on the Koi Growth Chart.
The other way is to check their scale. The growth of scales is proportionate to their general growth. You will notice annual marks forming on the scales at a similar time each year on the outer edges.
If you notice that your koi has lost its scale, you need to give it a closer look even if by using a microscope. Once you do that, you need to count the number of rings (annular rings) to derive the number of years the koi is.
It might even be older than the ascertained number. The scaling strategy for establishing koi age is more effective or accurate for younger ones – those at least 5 years old.
Another important factor to note when seeking to know the age of koi using their scale is that the female species might not add growth rings during reproduction.
Some might grow more after reproducing thus causing one growth ring to resemble a two.
Another accurate way to determine the age of koi is by examining its cross-section of the fin spine. It also has annular rings. The most commonly used is the second anal-fin spine.
You can do this without causing any permanent damage as the fin always grows back.
Examining the koi’s ear bone or otoliths is another way you can establish their age. They are in the cranial cavity and comprise of protein and calcium carbonate.
Of the three otoliths inside the koi’s inner ear, the largest pair is known as the sagittate. Many experts routinely use this one ascertaining age. Even in this one, you count the annular ring number.
You will notice the formation of white bands during summer and spring months while darker ones form in the winter.
You can approximate the koi’s age by counting the dark and light bands as one year.
How Old Is the Oldest Koi?
The oldest koi lived 226 years. Going by the name Koi Hanako, it was a beautiful scarlet colored koi of the female species.
Hanako passed on in 7th July 1977 aged 226 years.
Verification of her actual age was done through an analysis of her scales. This is akin to how dendrologists ascertain a tree’s age by counting the number of rings of wood growth.
So, they did the same just as we have explained earlier in the section above.
Final Words
The way you take care of your koi will determine how short or long it will live. Proper care entails providing adequate amounts of water, offering them high quality and correct foods, and always making sure that the water in the pond is clean.
It is also prudent to regularly clean the pond filter and get rid of all the debris on the water surface. Doing all these will go miles in making sure your koi not only remains healthy but also lives for long.
