Koi, or nishikigoi, are ornamental domesticated varieties of the common carp Cyprinus carpio.

Koi breeding originated in the 18th century in the Niigata prefecture of Japan. Farmers working the rice fields would notice that some carp were more brightly colored than others, capture them, and raise them. By the 20th century, a number of color patterns had been established, most notably the red-and-white Kohaku. The outside world did not become aware of the degree of development until 1914, when the Niigata koi were exhibited in the annual exposition in Tokyo. At that point, interest in koi exploded throughout Japan. The hobby of keeping koi spread worldwide after plastic bags and shipping of koi became both fast and safe for the fish. These factors enabled koi to be shipped worldwide with low mortality rates. Koi are now commonly sold in most pet stores, with higher-quality fish available from specialist dealers.

Koi varieties are distinguished by coloration, patterning, and scalation. Ghost koi, developed in the 1980s are metallic hybrids of wild carp and Ogon koi and are not considered true Nishikigoi. Butterfly koi, Longfin koi, or Dragon Carp were also developed in the 1980s and are notable for their long and flowing fins. They are actually hybrids with Asian carp and, like Ghost koi, are not considered true Nishikigoi.

The common carp is a hardy fish, and koi retain that durability. Koi are cold-water fish, so koi ponds have a meter or more of depth in areas of the world that become warm during the summer. In areas that have harsh winters, ponds that are a minimum of 1.5 meters (4 1/2 feet) are most common.

Koi's bright colors put them at a severe disadvantage against predators; a white-skinned Kohaku is a visual dinner bell against the dark green of a pond. Herons, kingfishers, raccoons, cats, foxes, and badgers are all capable of emptying a pond of its fish. A well-designed outdoor pond will have areas too deep for herons to stand in, overhangs high enough above the water that mammals can't reach in, and shade trees overhead to block the view of aerial passers-by. It may prove necessary to string nets or wires above the surface. A pond usually includes a pump and filtration system to keep the water clear.

Koi are an omnivorous fish and will often eat a wide variety of foods, including peas, lettuce, and watermelons.[1] Koi food is designed not only to be nutritionally balanced, but also to float so as to encourage them to come to the surface. When they are eating, it is possible to check koi for parasites and ulcers. Koi will recognize the person feeding them and gather around him or her at feeding times. They can be trained to take food from one's hand. In the winter, their digestive system slows nearly to a halt, and they eat very little, perhaps no more than nibbles of algae from the bottom. Their appetite will not come back until the water becomes warm in the spring. When the temperature drops below 50 degrees Fahrenheit (10 °C), feeding, particularly with protein, is halted or the food can go rancid in their stomach, causing sickness.

If kept properly, koi can live about 30–40 years. Some have reportedly lived up to 200 years. (Taken from the Wikipedia article.) Read More...

Here is some wonderful artwork by deviants that involve Koi fish. Some were found through a search and others were submitted to a Thumbshare forum thread. Please check out their artwork, and thank you to everyone who submitted! Enjoy!

PAINTINGS/DRAWINGS


PHOTOGRAPHY/MISC.