Koi carp

Koi are ornamental varieties of the common carp, a large cyprinid of the family Cyprinidae originally native to Eurasia and selectively bred in Japan for centuries into a spectacular range of color patterns in white, red, black, yellow, blue and metallic tones. They are among the most iconic of all pond fish. They are peaceful, sociable and long-lived, thriving in groups, and become tame enough to hand-feed. Their large adult size makes them strictly pond animals rather than aquarium fish. Koi require a large, deep, well-filtered pond with strong biological filtration to cope with their heavy waste output, and cool, well-oxygenated water. They are omnivores that root through substrate for invertebrates, plants and detritus, and readily take floating koi pellets, vegetables and treats. They can uproot pond plants. They spawn in spring by scattering adhesive eggs among vegetation, with no parental care.