Koi fish are colorful, ornamental versions of the common carp. Though carp domestication is believed to have begun in China as far back as the 4th century, modern Japanese koi are believed to date back to early 19th-century Japan where wild, colorful carp were caught, kept, and bred by rice farmers. There are now dozens of different color varieties of koi. Wild koi are native to the fresh bodies of water around the Black, Caspian, and Aral Seas. Domesticated in the 19th century, carp have now been introduced throughout the world. Koi are omnivorous feeders who will eat food found at all depths of water. The Japanese koi at the Kids’ Farm are fed a floating pellet, though they will also eat aquatic insects, algae, and plants.

Resource: https://nationalzoo.si.edu/animals/japanese-koi