Koi is a typical Japanese pond fish which you can find in almost any pond or river canal in Japan. There are two meanings for the Japanese word “Koi”, one being the name of the fish and the other meaning “love” or “care” (the kanji of the words are different). Koi is a freshwater fish which comes in both dull and bright variety of colors. It is seen in freshwater sources like ponds in a shrine or a nearby rivulet in grasslands. These Koi fish are native to Asia, especially to the Far East. Generally these fish are omnivorous. They feed on insects, algae, worms and others.
Japanese people sometimes have Koi in aquariums. Many people mistake Koi for Gold Fish due to their bright colors. However, goldfish and Koi are two different types of fish. Gold Fish naturally have golden color while Koi can change colors depending on weather conditions. Gold Fish and Koi belong to the same family called “Common Carp”. It is said that goldfish actually used to be the same as Koi and came in many colors. But, the goldfish were bred by the Chinese from the thousands of years ago to have specifically golden look and due to mutation and in-breeding, goldfish retained the permanent golden color while Koi remained the same in the wild. Goldfish are generally smaller in size when compared to Koi fish.
Koi ponds are specifically designed ponds for the ornamental Koi fish. It is an aesthetics driven design with brushes, vortexes, lines, filters and so on. They are well managed and cleaned up once in a while to stop algae from spreading. If you are interested tin what a Koi Pond looks like, you can download one of the famous apps from iTunes: The Koi Pond.