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Home > Fish > 16 Fascinating Koi Fish Facts You Need to Know!

16 Fascinating Koi Fish Facts You Need to Know!

koi fish

Koi fish are unique and beautiful animals that are popular all over the world. When you get down to it, there are far more to koi fish than first meets the eye. Some people think that koi fish are just giant goldfish, but that couldn’t be farther from the truth. Koi fish can live for decades, they represent good things for people all over the world, and they can be traded and sold for thousands of dollars. Koi fish are amazing animals that are fascinating to learn about.

Here are 16 incredible facts about koi fish you need to know.


The 16 Fascinating Koi Fish Facts

1. Koi Fish Can Come in a Variety of Different Colors

Koi fish are known for their beautiful coloring. Koi fish can come in a variety of different colors, including white, black, blue, red, cream, and yellow, or a mixture of all of the above. Each koi fish looks different. The color of an individual koi fish depends on its variety and its genetics. Koi fish collectors will choose and prize different koi fish based on their appearance and coloring.

Koi fish in a pond
Image Credit: imsogabriel, Pixabay

2. The World’s Largest Koi Fish Weighs Over 90 Pounds

Koi fish can grow incredibly large. Many mature koi fish reach lengths of 3 feet and can weigh dozens of pounds. The largest koi fish ever recorded weighed 91 pounds and was nicknamed Big Girl. This prize koi was sold to a koi fish enthusiast living in the United Kingdom.

3. Koi Fish Can Live 30 Years in Captivity

Unlike a typical fish, koi fish can live for an incredibly long time. If healthy, koi fish can live up to 30 years or more. Some captive koi fish have been found to live for 40 or 50 years. That makes koi fish some of the longest living fish in the world, and they can be owned by the same family for decades.

koi fish pond
Image Credit: bluefish_japan, Pixabay

4. One Koi Fish Reportedly Lived for 226 Years

There is a report that borders on myth that one koi fish managed to live for over 200 years! The fish in question was named Hanako and was allegedly born in 1791. Hanako didn’t pass away until 1977, making it 226 years old. At this point, it is impossible to verify these claims, but the story of Hanako continues to persist in koi fish legend to this day. Many people swear that this single koi lived for all of those years, but no other koi fish has lived as long as Hanako, so the claims seem a little fishy.

5. Koi Fish Are Considered Good Luck

In many cultures, koi fish are considered to be good luck. Particularly large, old, or beautiful koi fish are supposed to bring more luck to their owners than standard koi fish. Koi fish can also represent wealth and longevity. The associations with luck and wealth are some of the things that make koi fish so popular.

Koi Fish
Image Credit: Quang Nguyen Vinh, Pexels

6. There Are Dozens of Different Varieties of Koi Fish

There are over a hundred unique varieties of koi fish. Koi fish varieties are determined by their colors, patterns, and body confirmation. Koi fish can be bred and crossbred to produce particular and unique confirmations that make some fish more desirable than others. In this way, koi fish are similar to reptiles which are bred for morphologies or morphs. Koi fish collectors and enthusiasts will target certain types of varieties for their collections.

7. Koi Fish Are Related to Goldfish

Some people think that koi fish are just large goldfish. That is not entirely true. Koi fish are related to goldfish, but they are completely different. Both koi fish and goldfish are descended from a species of wild carp. The wild carp eventually became these two types of popular captive fish, and the common ancestor links these two fish to this day.

Orange and Red Koi Fish
Image Credit: Valeria Nikitina, Pexels

8. Koi Fish Can Get Sunburned

Koi fish prefer to live in water that is cool and shady. That is because koi fish actually have very sensitive skin. Since koi ponds are typically very shallow and located outside, koi fish can actually get sunburned! You don’t want your koi fish to get burned, so you should provide ample amounts of shade for your koi pond. Leaving your koi exposed to direct sunlight, especially during the summer or in hot environments, can lead to a fishy sunburn. Since there are no sunscreens designed for koi fish, you need to manage the amount of sunlight that koi get exposed to in order to protect their skin.

9. Koi Fish Like Having Friends

Koi fish are social animals. They like living in small groups of multiple fish. Koi fish do not like to be alone. However, koi fish can congregate in very large groups, which can be dangerous for the fish. When koi fish become too numerous, they can crowd each other out and lead to injury and even death. Despite this, koi fish absolutely want a few companions to swim around with.

koi and goldfish in the ornamental fish pond
Image Credit: HiTecherZ,Shutterstock

10. Koi Fish Will Eat Almost Anything

Koi fish are omnivores and are not picky about what they eat. Koi fish will eat almost anything from pieces of bread to fish food and insects. Many koi fish will float to the surface of the water to receive food. Koi fish are very versatile and flexible about what they eat, and they will routinely eat things from outside of the water.

11. Koi Fish Can Lay Thousands of Eggs at a Time

During mating season, fertile koi fish can lay thousands of eggs at one time. Some female koi can spawn tens of thousands of eggs. The hardiest koi fish can spawn 50,000 eggs or more. The ability to lay so many eggs makes koi fish easy to produce, and there are large numbers of koi fish all over the world. If the eggs are cared for properly, a mother koi can get half of the eggs to spawn. That can result in over 20,000 baby koi swimming around.

Koi fish eggs perched on red bricks during spawning season
Image Credit: Mr. Piyapong, Shutterstock

12. Enthusiasts and Breeders Will Pay Thousands for Good Koi Stock

The most expensive koi fish in the world once sold for $1.9 million. The fish was a special variety of ornamental koi called Kōhaku. Even outside of the most expensive varieties, koi fish can still be expensive. Many koi varieties sell for between $100 and $2,000 apiece. That is a lot of money for koi fish. Breeders, traders, collectors, and enthusiasts will pay even more for particular fish that will help their collection. Fish with good breeding stock and unique patterns can fetch thousands of dollars from the right buyers.

13. Prized Koi Are Often Passed Down Through Families

Since koi fish are so expensive and can live for so long, prized koi often end up in people’s wills. In Asia, where koi culture is more prevalent than in North America, it is not uncommon for the family koi fish to be passed down through the generations. Since koi can live for 30 years or more, they have the potential to be passed down more than once through a last will and testament. Receiving a particularly large or beautiful koi is considered good fortune and is a prized part of the inheritance process in some cultures.

koi fish pond water fall
Image Credit: MelissKeaneArt, Pixabay

14. Most Koi Fish Are Bred in Captivity

While koi are descended from the wild carp, there are very few wild koi in the world. Most koi fish are cultivated and bred in captivity. There are not many true wild populations of koi fish. While koi can be found living in retention ponds and canals in Asia, these koi were largely bred in captivity and released into certain areas. Some places feature “wild” koi on purpose because of their association with luck.

15. Koi Can Be Mean and Kill Other Fish

Koi fish often live in groups of other koi, but they don’t always play nice with other fish. Large groups of koi can become cliquey, and they will crowd out other freshwater fish. In some circumstances, koi can even gang up on foreign fish and attack and even kill them. Koi tend to get along very well with one another but not with other fish. There have been instances of koi killing goldfish that people try to pair with their koi. This is important to know if you are trying to stock a koi pond of your own.

Koi Fish Pond
Image By: linda chen, Pixabay

16. Koi Are Surprisingly Intelligent

Koi have already shown a lot of unique characteristics, but one of the most surprising is the fact that they are very intelligent. Koi have been shown to recognize faces. Koi can also be trained to appear at feeding time. Some koi have even reportedly learned to ring a bell to ask for snacks. Tame koi have learned how to surface and present their mouths so that they can literally eat out of a person’s hand. This shows that koi are more perceptive and intelligent than the average fish.


Final Thoughts

Unlike their ponds, koi fish show a surprising amount of depth. They are loved and appreciated by people around the world. Koi fish are surprising in many ways, from their intelligence to their appearance. The more you learn about koi fish, the more apparent it becomes why these fish are so popular and respected. The next time you spot a koi fish when you are out and about, you will know a lot more about them which can help you appreciate their uniqueness.

Featured Image Credit: Glorfmorph, Pixabay

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