Facts About Koi Fish

Facts About Koi Fish

Koi Fish: What’s elegant, regal, and can be found gracing outdoor ponds and water gardens throughout the world? The koi fish, of course! These big, bright fish have been around for hundreds of years and make a great addition to any suitable garden pond or large water feature.

Koi is an informal group name of the colored variants of C. rubrofuscus. Several varieties are recognized by the Japanese. Koi varieties are distinguished by coloration, patterning, and scalation. Some of the major colors are white, black, red, orange, yellow, blue, and cream. The most popular category of koi is the Gosanke, which is made up of the KohakuTaisho Sanshoku, and Showa Sanshoku varieties.

Facts About Koi Fish

Koi Fish Tattoo

Koi Fish Drawing

  • Experience Level: Intermediate
  • Size: Koi grow up to 36 inches (91 cm) long
  • Lifespan: They can live for more than 50 years and thrive in a wide range of water temperatures
  • Temperament: They are generally peaceful but may pick on slower fish
  • Origin: They’re a type of carp native to Japan
  • Did You Know: Koi can learn to recognize and take food from their pet parents

How do I set up my koi’s aquarium?

  • Koi grow quickly and get very large. Keep mature koi in an outdoor pond of at least 3 feet deep, with at least 50 gallons of water per fish.
  • Young koi can be kept indoors in an aquarium of at least 29 gallons.
  • Put the aquarium in a quiet area out of direct sunlight and drafts.
  • Cover the aquarium with a hood to reduce evaporation and splashing and to keep fish from leaping out.
  • To transfer new koi to the aquarium, float them in the water inside their bag for about 10 minutes so they can acclimate to the new water temperature.
  • If you’re introducing koi to an existing school in an aquarium or pond, quarantine the new fish in a separate body of water for 2 to 4 weeks to be sure they are healthy.
  • On moving day, use a net to transfer the koi so old water doesn’t mingle with new water.
  • Whether they live indoors or outdoors, add no more than 3 new koi at a time.


  • Follow the manufacturer’s instructions for choosing and setting up the right size filter for your koi habitat.
  • An aquarium filter should be able to process all of the water in the tank 3 to 5 times an hour. For example, the filter in a 20-gallon tank would need to push through at least 60 gallons of water each hour.
  • Add beneficial bacteria supplements to help break down waste in the habitat.
  • PetSmart offers free aquarium and pond water testing. Just bring in a sample of your water, and we can test the quality within minutes.

Heat & light

  • Outdoor koi are hardy and will hibernate under ice in winter as long as their pond is deep enough to not freeze completely. (They won’t survive in solid ice.)
  • Your koi’s pond should be partially shaded.
  • Indoor koi prefer water between 65 and 75 degrees Fahrenheit.
  • Install a light inside an indoor aquarium to illuminate it for 8 to 12 hours a day.

Water temperature

Koi are pretty temperature-resistant— they can even hibernate under ice in winter. Just be sure your pond is at least three feet deep— otherwise, it could freeze solid, and koi aren’t that tough. When they live indoors, koi prefer cool water—between 65 and 75 degrees F (18 to 24 C).

How do I keep my koi healthy?

If your outdoor koi don’t seem to be eating in the winter, don’t worry; it’s normal for them to stop eating at temperatures below 40 F.

Be sure to contact a veterinarian if you notice any of these symptoms:

  • Unusual swimming pattern
  • Thinness or decreased appetite
  • Abdominal swelling
  • Inflamed or discolored skin or fins
  • Fins clamped to sides of body
  • Scraping body on rocks (flashing)


  • Fish and aquatic animals can transmit disease to humans. Wash your hands with soap and water before and after interacting with your aquarium. Children, pregnant women, elderly people and people with immune-system problems should take extra care.
  • Keep fish away from food and areas where food is prepared.
  • Never release fish into the wild. They won’t adapt well and can damage natural habitats.
  • Thoroughly wash your hands with warm, soapy water before and after contact with any pet or its habitat.
  • Adults should assist children with hand washing after contact with a pet, its habitat or aquarium water.
  • Do not use soaps or detergents to clean aquarium or décor, since they are toxic to fish.

Pets purchased at PetSmart are part of our exclusive Vet Assured™ program, designed by PetSmart veterinarians to help improve the health and well being of our pets. Our vendors meet a high standard in caring for pets and screening them for common illnesses. This program also includes specific standards for in-store pet care. If your pet becomes ill during the initial 14-day period, or if you’re not satisfied for any reason, PetSmart will gladly replace the pet or refund the purchase price.

Koi Fish For Sale

If you know someone who has a pond, chances are they keep a couple of Koi to brighten it up.

Koi fish are some of the most common, well-known fish to keep in outdoor garden ponds.

In Japan where they were first bred they are highly prized and are even the main subjects of many myths and artwork.

Although they are directly related to goldfish, it would be a big mistake to assume that they have the same level of care. These fish could never live in a tank, they need an outdoor pond.

Do you think you are ready to open your pond to a few Koi? Read on to discover the best possible way to care for these gorgeous, long-living carp.

Category Rating
Care Level: Intermediate
Temperament: Peaceful
Color Form: Typically white or silver with red, gold or orange markings
Lifespan: 30-50 Years
Size: 24-36″
Diet: Omnivorous
Family: Cyprinidae
Minimum Tank Size: 250 Gallons
Pond Set-Up: Heavily planted outdoor water garden
Compatible: Other carp, game fish and amphibians

Koi Fish Art

Koi Fish Art

Koi are an ornamental species of fish that descend from the carp. In the 1600s, Chinese farmed carp in rice paddies, a practice that traveled to Japan, where the Japanese noticed odd color variations in some of the carp and bred them, creating the koi species. Koi used to only be found in red, white, black and blue, but have since been bred in different combinations of all the colors in the rainbow.

The very first koi were bred almost exclusively in Japan. The Japanese bred koi fish for perfection, and some species were even prized in the collections of royal families and immortalized in royal artworks. It wasn’t until the 1900s that koi began to be bred parts of Europe, the United Kingdom and the United States.

Where Can I Buy a Koi Fish?

These days, koi are still one of the most popular and beloved types of fish in the world and are widely available no matter where you live. Pet koi typically come from commercial farms in Europe, Asia and the United States and are readily available at most pet stores. There are also specialized koi breeders and farms that you can buy koi from.

Depending on the color koi you’re looking for, you can expect to pay anywhere between five dollars and fifteen dollars for a single koi from a pet store. Pricing from breeders can vary depending on the size, color and type of koi you’re looking to buy.


How Big do Koi Get?

Koi fish are quite large and, with proper care, can grow to be between two and three feet in length. The Chagoi variety of koi get even larger – up to four feet long in some cases. Young koi can be kept in large indoor aquariums but need to be transferred to a large pond as they grow. They are a heavy-bodied fish with an average weight of around 35 pounds. Because they’re such a large fish, koi ponds need to be large. A good rule of thumb is that a pond should contain 500 to 1,000 gallons of water for each adult koi it houses.

In order to thrive, Koi require high-quality, clean water in their ponds (which can be achieved using a filtration system designed for outdoor koi pond use). When properly raised and cared for, a koi fish can live up to 20 years, sometimes longer.

Koi Fish Meaning

  1. Koi fish were originally brought to Japan as a food source
  2. Koi fish are decedent’s of the hardy Carp which is so adaptable it can be found all around the world.
  3. Koi fish were developed by farmers who noticed the bright color patches on carp and breed them to get the beautiful fish we have today
  4. Koi fish were brought to the worlds attention after one was given to the Japanese emperor as a gift in 1914 to grace the imperial palaces mote.
  5. Koi fish and Goldfish are distant cousins as they both decent from Carp, but goldfish came about long before koi fish did.


  1. The largest koi fish ver recorded was a whooping four feet long and 91 pounds! The monster sized fish was later sold to the koi enthusiast Geoff Lawton where she received the name Big Girl.
  2. Koi fish are omnivores who will eat just about anything you give them including lettuce and watermelon
  3. Koi fish can actually get sun burns so make sure they have some shade on sunny days!
  4. Koi fish not only look the best in a group they also enjoy having other koi fish around. Make sure to keep an eye out if you put any other types of fish in your pond though because koi have been known to bully non-koi pond mates.
  5. The oldest koi fish ever was a koi named Hanako was born in 1791 and didn’t die until 1977 that means she lived to be 226!

Carp are a large group of fish originally found in Central Europe and Asia. Various carp species were originally domesticated in East Asia, where they were used as food fish. Carp are coldwater fish, and their ability to survive and adapt to many climates and water conditions allowed the domesticated species to be propagated to many new locations, including Japan. Natural color mutations of these carp would have occurred across all populations. Carp were first bred for color mutations in China more than a thousand years ago, where selective breeding of the Prussian carp (Carassius gibelio) led to the development of the goldfish (Carassius auratus).

The Amur carp (Cyprinus rubrofuscus), a member of the cyprinid family species complex native to East Asia, was aquacultured as a food fish at least as long ago as the fifth century BC in China, and Jin Dynasty (fourth century AD) texts mentioned carp with various colors. The Amur carp was previously recognized as a subspecies of the common carp (as C. c. haematopterus), but recent authorities treat it as a separate species under the name C.

Are koi fish dangerous to humans?

It is a question as old as koi are, which is over one hundred years, and the answer is simple – yes koi do bite. A koi fish bite will only tickle you, but their little nibbles help them eat food from the bottom of your pond and can be dangerous to other fish.

Are koi fish good to eat?

You can eat koi, it’s a form of carp after all, but you probably wouldn’t want to. One, koi is considered sacred in places like Japan and a good luck omen in other countries in SE Asia. Koi are sold as decorative, ornamental or sacred fish, to be kept as pets.