Facts About Koi Fish

Written by:

PetMD Editorial
Published: February 11, 2016

By Kali Wyrosdic

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.

Learn more about the koi fish, including where to find koi and what type of habitat your koi will need to survive, below.

Where Do Koi Come From?

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.

Can Koi Live with Other Fish?

Koi are docile, social fish that enjoy living in pairs or groups. When considering whether or not to add a new fish to an existing habitat, always make sure that their environmental and nutritional requirements are the same as the current fish, and, in the case of adding a koi fish to an existing pond, make sure that the size of your pond is large enough to support a full-grown koi. Koi are truly friendly and will not eat other fish or fight with each other. If you are mixing species, make sure the same can be said for the other types of fish in your pond before adding koi. Not only are koi friendly to other fish, but they may also come up to the surface to say hello when they see their owner or when it’s time to eat. Some koi even like to be pet and will come to the surface for a little pat on the head.

Can You Eat Koi?

Chinese farmers originally bred koi for eating, and it wasn’t until the 1800s that the fish was bred as a pet for its unique and striking colors. Though they aren’t poisonous to eat, it’s advised that the types of koi that are kept as pets in water gardens or backyard ponds shouldn’t be eaten.

Image:  / Shutterstock