Assorted Koi

(Cyprinus carpio) 

Koi are ornamental varieties of domesticated common carp that originated in Japan. They are kept for decorative purposes in outdoor ponds with very clean, oxygenated water and plenty of shade (the fish are susceptible to sunburn!). There are over 100 varieties of koi, which can be red, white, black, yellow, brown, gray, and green, and many combinations thereof. Koi resemble oversized goldfish and, in fact, koi and goldfish are both types of carp. 

In the 1600s, Chinese farmed carp in rice paddies as a food source, a practice that traveled to Japan. The Japanese noticed odd color variations in some of the carp and bred them, creating a rainbow spectrum of koi species. Koi were prized by royalty; by the 1900s, koi were being bred in Europe, England, and the US. By the 1960s, keeping koi as a hobby had caught on around the world. Today, they are kept as pets on 6 out of 7 continents. 

Koi are culturally significant and represent love and friendship in Japan. Some koi can live over 200 years, so they are passed down from generation to generation and considered a family heirloom in Japan. Varieties of koi are distinguished by their coloration and scale pattern. They are social, "schooling" fish.

https://animals.sandiegozoo.org/animals/koi