Koi

Koi are big, friendly-looking fish famous for their bright patterns of white, red, orange, yellow, black, and even shiny gold. They are a special kind of carp, and people keep them in ponds and water gardens so they can enjoy watching them glide and swirl. In Japan they are called nishikigoi, which means “brocaded carp”, because their colours look like beautiful patterned cloth.

Wild carp are plain and greeny-brown, but long ago fish farmers in the snowy region of Niigata, Japan, noticed that a few of their carp had splashes of colour. They carefully bred these colourful fish together, again and again, until they had created the dazzling koi we know today. Now there are more than a hundred different kinds, each with its own name and pattern.

Koi are not fussy eaters. They are omnivores, which means they nibble a bit of everything, from algae and soft water plants to insects, worms, and the floating pellets that pond keepers scatter for them. They use their mouths like little vacuum cleaners, sucking food off the bottom of the pond and sifting out the tasty bits.

Koi are cold-water fish and very hardy. In warm weather they swim near the surface and may even learn to take food from a gentle hand. When winter makes the pond icy cold, they slow right down, tuck near the bottom where the water is a little warmer, and quietly wait for spring.

Koi are pets and pond fish, so wild scientists have not given the ornamental koi its own conservation rating. Its wild ancestor, the Amur carp, still swims in rivers and lakes across eastern Asia and is listed as Least Concern, which means it is doing well. Cared-for koi can live for many years, and some are handed down from parents to children like a treasured, living heirloom.