Fun Facts You Might Not Know About Koi

From their ancient origins in East Asia to their symbolic significance in various cultures, koi have carved a unique place in the world of aquatic life. While some say they’re high maintenance, quite the opposite is true. Koi are rather hardy which is part of the reason why they’re the most common fish in backyard ponds around the world. Their amazing colors and patterns are the predominant reason for their popularity. Let’s dive into their world and learn a few fun facts about koi that you might not know.

koi in pond - fun facts about koi



Koi can reach a maximum size of 40 inches, with anything over 28 inches considered jumbo. Depending on the size of their habitat and how aggressively they eat, the jumbo size can be reached in a matter of four to five years! Koi can, and will, outgrow smaller water gardens, so keep this in mind when adding koi to your pond.



Koi can generally survive in water temperatures from 35 degrees to 86 degrees Fahrenheit (and possibly higher). Surprising to some people, koi can be overwintered in a pond provided the pond is at least two feet deep and a hole is kept open in the ice for the exchange of gases. Baby koi might not make it through winter due to their lack of constitution. In Japan, quality baby fish are taken into heated greenhouses for winter.



Koi will accept almost any commercial food as well as graze on algae and other plant matter. They also enjoy a wide variety of fresh fruits and vegetables, as well as night crawlers, silkworm larvae, and various insects.


Here’s a few more fun facts of koi that might surprise you:

  • The largest koi ever recorded was 91 pounds and four feet long.
  • Some koi outlive their owners, although most live to 30 or 40 years of age.
  • The oldest koi was named Hanoko and lived to be 226 years old!
  • A black koi is said to bring good luck.
  • Koi are very smart and will recognize the person who feeds them.
  • You can train koi to eat out of your hand if you’re patient.
  • Koi are prone to sunburn so it’s important to shade the surface of the pond with plants like waterlilies, water lettuce, and water hyacinth.
  • Female koi are more playful than their male counterparts.
  • Koi have teeth, located at the back of their throat.
  • Although koi are popular in Japan, they originated in China around the fourth century.