16 Fascinating Koi Fish Facts You Need to Know

Koi fish are unique and beautiful animals that are popular all over the world. Some people think that koi are just giant goldfish, but that couldn’t be farther from the truth. For starters, these 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 are amazing animals that are fascinating to learn about.

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

Top 16 Fascinating Koi Fish Facts

1. Koi Can Come in a Variety of Different Colors

Koi fish can come in a variety of different colors, including white, black, blue, red, cream, and yellow, or a mixture of these. Each one looks different. The color of an individual koi depends on its variety and genetics. Collectors will choose and prize different koi fish based on their appearance and coloring.

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.¹ This prize koi was sold to an enthusiast living in the United Kingdom.

3. Koi Fish Can Live 30 Years in Captivity

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

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. She didn’t pass away until 1977, making her 226 years old.² At this point, it is impossible to verify these claims, though the story of Hanako continues to persist in koi legend to this day. Many people swear that this single koi indeed lived for all those years, but since no other koi fish has lived as long as Hanako, the claims seem a little fishy.

5. Koi Fish Are Considered Good Luck

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

6. There Are Dozens of Different Varieties of Koi Fish

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

7. Koi Fish Are Related to Goldfish

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

8. Koi Fish Can Get Sunburned

Koi prefer to live in water that is cool and shady because they have sensitive skin. Since koi ponds are typically shallow and located outside, these fish can actually get sunburned! You don’t want this to happen, so you should provide ample amounts of shade for your koi pond. Leaving your fish 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 your pets get exposed to in order to protect their skin.

9. Koi Fish Like Having Friends

Koi fish are social animals. They prefer living in small groups and do not like to be alone. However, koi can sometimes congregate in large groups, which can be dangerous for the fish. When they become too numerous, they can crowd each other out and lead to injury and even death. That said, koi fish need at least a few companions to swim around with.

10. Koi Fish Will Eat Almost Anything

Koi are omnivores and are not picky about what they consume. They 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. They are versatile and flexible about what they eat and will routinely snatch things from outside the water.

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

During mating season, fertile koi can lay thousands of eggs at one time. Some female koi can spawn tens of thousands of eggs. The hardiest fish can spawn 50,000 eggs or more. The ability to lay so many eggs makes these fish easy to produce, so there are large numbers of koi 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.

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. This was a special variety of ornamental koi called Kōhaku. Even outside of the most expensive varieties, though, koi fish can still be expensive. Many varieties sell for between $100 and $2,000 apiece. That is a lot of money for fish. Breeders, traders, collectors, and enthusiasts will pay even more for particular koi 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 can be passed down more than once. Receiving a particularly large or beautiful koi is considered good fortune and a prized part of the inheritance process in some cultures.

14. Most Koi Fish Are Bred in Captivity

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

• Related Read: Can Koi Fish Live in Tanks?

15. Koi Can Be Mean and Kill Other Fish

Koi tend to get along well with one another but not with other fish. Large groups of koi can become cliquey, and they will crowd out other freshwater fish. In some circumstances, koi can gang up on foreign fish and attack and even kill them. This is important to know if you are trying to stock a koi pond.

16. Koi Are Surprisingly Intelligent

Koi have obvious unique characteristics, but one of the most surprising may be the fact that they are quite intelligent. Koi fish have been shown to recognize faces. They can also be trained to appear at feeding time. Some have even reportedly learned to ring a bell to ask for snacks. Tame koi have learned how to surface and present their mouths so 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 show a surprising amount of depth! They are loved and appreciated by people around the world. These fish are surprising in many ways, from their intelligence to their appearance. The more you learn about koi, the more apparent the reason that these fish are so popular and respected. The next time that you spot a koi when you are out and about, you will know a lot more about them, which can help you appreciate their uniqueness.

• Related Read: Majestic Koi Fish Names for Their Beautiful Colors

Featured Image Credit: Glorfmorph, Pixabay