5 Incredible Facts About Koi Fish

Koi fish are intelligent creatures and come in many colors. They can live for over 50 years, grow up to 3 feet long and sell for thousands of dollars.

Jan 19, 2024By Tanya Taylor
incredible facts about koi fish

Many of us have encountered Koi fish. You can find these spectacular creatures in backyard ponds and ornamental gardens all around the globe. Koi, also known as Koi Carp, is associated with Japan, where the natives have been breeding them for hundreds of years. I love these freshwater fish because not only are they pretty, but they are also a symbol of good luck and prosperity. If you want to know more about these beautiful aquatic beings, join me to discover 5 fascinating facts about koi fish.

1 - Koi Can Outlive Their Owners

wild koi fish
Photo by: Sora Sagano on Unsplash

Koi fish have a reputation for longevity, and in Japan, some even pass through families for generations as heirlooms. Koi live longer in Japan because they have superior genes and live in the ideal climate with the perfect diet. Due to their cultural traditions, Japanese owners are also more experienced in Koi care. In Japan, many Koi reach 70-100 years old.

Domestic Koi living outside Japan generally have a shorter lifespan, but with the correct care and attention, they can live between 15 and 40 years. The world's oldest Koi fish recorded was Hanako, a female scarlet Koi who was 226 when she died in 1977.

These ornamental fish are incredibly hardy - they’re parasite-resistant, handle stress well and adapt seamlessly to changes in water conditions. Koi can survive outside during cold winters by lingering at the bottom of their pool, where they enter an almost hibernation state. Their periods of little activity may be one of the crucial factors in their longevity.

2 - Koi Are One of The Largest Domestic Fish

koi fish in pond
Photo by: Ricky Davis on Unsplash

Koi fish can grow to incredible sizes, so it's no wonder they have a reputation as one of the largest domestic fish. Standard adult Koi measure 12 - 15 inches long, Japanese Koi can reach 22 - 26 inches, and Jumbo Koi can grow to a whopping 36 inches long.

Small Koi species generally grow faster than large ones, and their size depends on their diet and environment. A Koi fish with lots of space and a rich diet will generally grow longer than one in a small pond with a basic diet. Koi are omnivores, meaning they will eat almost anything and thrive on a varied diet.

The world's largest Koi carp is called Big Girl. She's a Jumbo Koi from Japan - but now lives with a breeder in the UK. Measuring 4 ft long and weighing 90 lb, she certainly lives up to her name and eats around 1 lb. of food daily.

3 - Koi Are Friendly and Intelligent

colorful koi fish
Photo by:Daniel on Unsplash

According to several studies and many owner testimonies - Koi is one of the most intelligent domestic freshwater fish. The research is still in the early stages, but these elegant fish are proving to be star pupils in laboratory tests. During the tests, Koi quickly learned how to navigate mazes and puzzles and even to ring a bell to win tasty rewards. These preliminary results indicate that Koi have a fantastic long-term memory.

If you’ve spent time around Koi fish, you will know they have heaps of personality, and I would even call them dog-like. These beautiful fish enjoy interacting with people and Koi form bonds with humans easily. They can identify faces, eat from your hand, and many of them love it when you pet them. They develop a strong bond with their owner and follow them around the pond, angling for affection or treats. Koi are the ideal choice if you’re looking for fish with huge personalities.

4 - Koi Fish Are Unique

koi fish on surface
Photo by:Jason Leung on Unsplash

There’s no denying that Koi fish are beautiful and majestic creatures. They're one of the most distinctive domestic freshwater fish due to their size and striking colors. You may find it hard to believe, but they were once dull gray, dark brown and black colored, just like standard carp. But, after lots of selective breeding, Japanese farmers eventually produced Koi in many colors, and now there are over 100 varieties.

Modern Koi are single, bi, tri, or multi-colored, and you find them in blue, red, white, orange, black, cream, yellow, and metallic colors. They are usually covered in extravagant swirling patterns, spots or splodges - each like a unique artwork. These pretty fish play a huge part in Japanese art and culture - and each Koi fish color has a different meaning.

Orange and white Koi are called Kohaku and symbolize a successful career. Asagi Koi represent strength and prosperity and are tricolored, usually pale blue, white and orange. Silver Ogon Koi represents good business and wealth, black Kumonryu fish represents strength, and golden Yambuki fish represent wealth and riches.

5 - Show Koi Can Cost Thousands Of Dollars

koi fish shoal
Photo by: David Dvořáček on Unsplash

Koi fish are also known as Nishikigoi in Japan, which translates as living or swimming jewel. While Koi may look like giant, extravagant goldfish, they can sell for eye-watering prices at collector’s auctions. Some Koi fish sell for millions, and the most expensive one sold for $1.8 million in the All Japan Koi Show in 2017.

Don’t worry - not all Nishikigo cost a small fortune. You can buy a standard domestic Koi reasonably cheaply, for around $8 - $50, and large ornate ones cost over $100. It’s the prized Japanese show Koi, which usually fetches incredible prices.

A Koi’s value depends on many factors, including:

  • Lineage - Like pedigree dogs - a well-bred, purebred Koi fetches higher prices.
  • Body shape - A high-quality Koi is streamlined and elegant with a symmetrical body and no abnormalities.
  • Size and age - Mature Koi are larger and generally more expensive.
  • Colors and markings - These are some of the most sought-after features in Koi, and the most beautiful and extravagant ones have a higher price tag. High-quality Koi have deep colors and well-defined patterns. Koi with unique features are also more sought after.
  • Origin - Pond-raised Koi are affordable and readily available, while the finest Koi generally come from Japan.
Tanya Taylor
By Tanya Taylor

Tanya is a trusted animal care professional and has devoted her life to animals. In her 25-year career, she’s worked with all kinds of creatures in many environments, including three years caring for small animals as a veterinary nursing assistant and five years birthing down racehorses.

She is an expert farm and dog sitter - and has spent many hours volunteering at her local pony sanctuary. Tanya is originally from Liverpool in the UK, but now she lives in Ibiza, Spain, with her cheeky red terrier Leo and three Leopard tortoise hatchlings, Ninja, Tiny, and Orwell.