What does koi mean?
Koi are domesticated varieties of the common carp, most famous for their vivid colors, flowing fins, and graceful movement. Although the word is strongly associated with Japan, where koi cultivation developed into a refined tradition, these ornamental fish are now kept in ponds and water gardens around the world. The term generally refers to the fish rather than to the species as a whole, so a colorful domesticated fish may be called a koi while an ordinary wild fish remains a carp. Koi are often described as hardy and long-lived, although their care requires suitable water quality, adequate space, and protection from predators. In garden and aquarium settings, their appearance has made them symbols of calm, beauty, and good fortune. The word is usually treated as an uncountable plural, with kois also accepted in formal and descriptive writing.
nounA domesticated variety of carp, usually kept in ornamental ponds and noted for its varied colors and markings. The term is especially associated with Japanese-bred fish, though koi are now kept worldwide.
- A domesticated, ornamental carp, typically brightly colored and kept in ponds.
- Any fish of the ornamental carp variety, including those bred in the Japanese tradition.
"A group of koi glided beneath the lilies in the garden pond."
"She watched the koi circle the feeder in the shallow pond."
"The Japanese garden was designed around a long pool filled with koi."
Koi is the usual plural form; kois is accepted in formal and descriptive writing.
"Many koi live in the ornamental pond."
Koi are not a different species: they are ornamental varieties of the common carp, selectively bred over generations for their colors, patterns, and graceful swimming.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does koi come from?
The English word koi comes from Japanese, where koi (鯉) means carp. The Japanese term reflects a broader East Asian tradition of carp cultivation, especially the development of brightly colored ornamental varieties in Japan. English speakers adopted the term in the context of Japanese gardens and the international ornamental-fish trade, where koi became the established name for these decorated carp.
How koi is actually used
The usual plural is koi; kois is also accepted. In English, koi most often refers to the ornamental fish rather than to wild carp generally. The term is especially common in descriptions of Japanese gardens and aquarium keeping.
Easily confused with koi
Carp is the broader term for the fish species and its wild or less ornamental varieties, while koi usually refers to domesticated, often brightly colored carp.