Domestic Koi Fish Fun Facts

Large Orange KoiKoi fish are a domesticated breed of carp chosen for their colors. The first mention of colored carp is made in the Japanese history book Nihon Shoki in 720. Nihon Shoki claims that koi were first bred by the Emperor in the first century AD. More than 1,000 years ago, carp were bred for their color in China, as well, and those mutations eventually led to the goldfish.

In the 19th century, a Japanese breeder began to create even more variations on black and orange koi. Some of these variations are blue, yellow, red on white, and metallic. The world outside of Japan was unaware of these new koi until 1914, when koi fish were displayed at an exhibition in Tokyo. Since then, hobbyists in countries all over the world have enjoyed raising and breeding koi.


Adult Koi in PondAlthough you can start out by putting your koi in an aquarium, they need to be transferred to an outdoor pond when they get bigger. Most koi end up being two or three feet in length and up to 35 pounds. Some koi, though, can grow up to four feet long. A pond generally needs to be large, preferably 500 to 1,000 gallons per fish. When well cared for, koi can live up to 20 years.

Koi are also known as nishikigoi, meaning “carp” and “brocaded/elegant carp” respectively. Until recently, other terms were also used for koi, such as irokoi (“colored carp”), moyokoi (“patterned carp”), and hanakoi (“floral carp”). Koi is a homophone in Japanese with a word that means love and affection. For this reason, koi are a symbol of love and friendship in Japan.


Adult Koi SpeckledAlthough koi were initially bred by farmers as a food source, their beautiful colors and peaceful nature soon made them cherished as pets. Because koi swim slowly and don’t race to eat the food sprinkled on the top of their pond, but rather take their time to eat, they are said to nurture inner harmony. It is said that to be a koi fish is to be a fish who has succeeded in life. In addition to love, they symbolize success and ambition. New homes may have koi ponds installed to signify that the owner is successful and happy.

If you’re interested in ornamental fish, please check out our blog post about the history of the goldfish!


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