, }} or more specifically , literally "brocaded carp"}}, are ornamental varieties of domesticated common carp (''Cyprinus carpio'') that are kept for decorative purposes in outdoor koi ponds or water gardens.

Koi varieties are distinguished by coloration, patterning, and scalation. Some of the major colors are white, black, red, yellow, blue, and cream. The most popular category of koi is the ''Gosanke'', which is made up of the Kohaku, Taisho Sanshoku, and Showa Sanshoku varieties.

History

Cyprinus carpio or the common carp is a species of fish from the family Cyprinidae. The origins of the common carp trace to the Caspian Sea, where the fish naturally migrated to the Black and Aral Seas, east to eastern mainland Asia and west as far as the Danube River. Within the same family, the Prussian carp (''Carassius gibelio'') were first bred for color mutations in China more than a thousand years ago, where selective breeding led to the development of the goldfish. This is the first known instance of selective breeding to produce ornamental fish.

Various carp species were originally domesticated in East Asia, where they were used as food fish. The ability of carp to survive and adapt to many climates and water conditions allowed the domesticated species to be propagated to many new locations including Japan. Natural color mutations of these carp would have occurred across all populations.

The common carp was aquacultured as a food fish as at least as far back as the 5th century in China. The common carp was also known to have been aquacultured in Europe by the Roman Empire, which could have spanned a time period of 27 BC to 400 AD. Common carp were first bred for color in Japan in the 1820s, initially in the town of Ojiya in the Niigata prefecture on the north eastern coast of Honshu island. By the 20th century, a number of color patterns had been established, most notably the red-and-white ''Kohaku''. The outside world was not aware of the development of color variations in koi 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 eventually spread worldwide. Koi are now commonly sold in most pet stores, with higher-quality fish available from specialist dealers.

Extensive hybridization between different populations has muddled the historical zoogeography of the common carp. However, scientific consensus is that there are at least two subspecies of the common carp, one from Western Eurasia (''Cyprinus carpio carpio'') and another from East Asia (''Cyprinus carpio haematopterus''). One recent study on the mitochondrial DNA of various common carp indicate that koi are of the East Asian subspecies. However another recent study on the mitochondrial DNA of koi have found that koi are descended from multiple lineages of common carp from both Western Eurasian and East Asian varieties. This could be the result of koi being bred from a mix of East Asian and Western Eurasian carp varieties, or koi being bred exclusively from East Asian varieties and being subsequently hybridized with Western Eurasian varieties (the butterfly koi is one known product of such a cross). Which is true has not been resolved.

Etymology

The word ''koi'' comes from Japanese, simply meaning "carp". It includes both the dull grey fish and the brightly colored varieties. What are known as koi in English are referred to more specifically as ''nishikigoi'' in Japan (literally meaning "brocaded carp"). In Japanese, "koi" is a homophone for another word that means "affection" or "love"; koi are therefore symbols of love and friendship in Japan. An example of this can be seen in the short story by Mukōda Kuniko, "Koi-san". Koi tattoos have also become a popular trend throughout the world.

Varieties

Koi varieties are distinguished by coloration, patterning, and scalation. Some of the major colors are white, black, red, yellow, blue, and cream. While the possible colors are virtually limitless, breeders have identified and named a number of specific categories. The most popular category is Gosanke, which is made up of the ''Kohaku, Taisho Sanshoku'', and ''Showa Sanshoku'' varieties.

New koi varieties are still being actively developed. Ghost koi were developed in the 1980s, and have become very popular in the United Kingdom, they are a hybrid of wild carp and Ogon koi, and are distinguished by their metallic scales. Butterfly koi (also known as Longfin koi, or Dragon Carp) were also developed in the 1980s, and are notable for their long and flowing fins. They are hybrids of koi with Asian carp. Butterfly koi and Ghost koi are considered by some to be not true Nishikigoi.

The major named varieties include: A white-skinned koi, with large red markings on the top. The name means "red and white;" kohaku was the first ornamental variety to be established in Japan (late 19th century). Very similar to the Kohaku, except for the addition of small black markings called . This variety was first exhibited in 1914 by the koi breeder, Gonzo Hiroi, during the reign of the Taisho Emperor. In America, the name is often abbreviated to just "Sanke". The kanji, 三色, may be read as either ''sanshoku'' or as ''sanke''. A black koi with red (''hi'' 赤) and white (''shiroji'' 白地) markings. The first Showa Sanke was exhibited in 1927, during the reign of the Showa Emperor. In America, the name is often abbreviated to just Showa. The amount of ''shiroji'' on Showa Sanke has increased in modern times (''Kindai Showa'' 近代昭和), to the point that it can be difficult to distinguish from Taisho Sanke. The kanji, 三色, may be read as either ''sanshoku'' or as ''sanke.'' Any koi with a solitary red patch on its head. The fish may be a Tancho Showa, Tancho Sanke, or even Tancho Goshiki. Named for the Japanese crane (''Grus japonensis'') which also has a red spot on its head. lit. 'Tea-colored' koi ranging in color from pale olive-drab green or brown to copper or bronze and more recently darker, subdued orange shades. Famous for its docile, friendly personality and large size, it is considered a sign of good luck among koi keepers. A koi that is light blue above and usually red, but also occasionally pale yellow or cream, generally below the lateral line and on the cheeks. The Japanese name means pale greenish-blue, spring onion colour, or indigo. Sometime incorrectly written as 浅黄 (light yellow). A black koi with a white, red, or yellow markings. Zebra colour. The oldest attested form is the yellow form, called in the 19th century, but renamed by Elizaburo Hoshino, an early 20th century koi breeder. The red and white versions are called and respectively. The word ''utsuri'' means to print (the black markings are reminiscent of ink stains). Genetically the same as Showa but lacking either red pigment (Shiro Utsuri) or white pigment (Hi Utsuri/Ki Utsuri) A white-, red-, or yellow-skinned koi with black markings . The Japanese name means "tortoise shell," and is commonly written as べっ甲. The white- red- and yellow varieties are called and respectively. May be confused with the Utsuri. A dark koi with red (Kohaku style) hi pattern. The Japanese name means "Five Colours". Appears similar to an Asagi with little or no Hi below the lateral line and a Kohaku Hi pattern over reticulated (fishnet pattern) scales. The base color can range from nearly black to very pale sky blue. The Japanese name means "Autumn green." The Shusui was created in 1910 by Yoshigoro Akiyama（秋山　吉五郎）, by crossing Japanese Asagi with German mirror carp. The fish has no scales, except for a single line of large mirror scales dorsally, extending from head to tail. The most common type of Shusui have a pale, sky-blue/gray color above the lateral line and red or orange (and very, very rarely bright yellow) below the lateral line and on the cheeks A koi with metallic (glittering metal-flake appearing) scales. The name translates into English as "gold and silver scales." Often abbreviated to Ginrin. There are Ginrin versions of almost all other varieties of koi, and they are fashionable. Gin-rin refers to sparlking, glittering scales as opposed to the smooth, even metallic skin and scales seen in the Ogon varieties. Recently these characteristics have been combined to create the new "ginrin Ogon" varieties. A "catch-all" term for koi that cannot be put into one of the other categories. This is a competition category and many new varieties of koi compete against each other within this one category. Also known as A metallic koi of one color only. (''hikarimono'' 光者). The most commonly encountered colors are gold, platinum, and orange. Cream specimens exist but are very rare. Ogon compete in the Kawarimono category and the Japanese name means "Gold." The variety was created by Sawata Aoki in 1946 from wild carp he caught in 1921. Recently the metallic skinned Ogon is being crossed with ginrin scaled fish to create the ginrin Ogon with metallic skin and sparkling (metal flake) scales. （literally "Nine Tattooed Dragons"） Kumonryu is a black doitsu scaled fish with curling white markings. The patterns are thought to be reminiscent of Japanese ink paintings of dragons. They famously change colour with the seasons. Kumonryu compete in the Kawarimono category. A light blue/gray koi with copper, bronze, or yellow (Kohaku style) pattern, reminiscent of autumn leaves on water. The Japanese name means "fallen leaves." A white fish with Kohaku style pattern with blue or black edged scales only over the hi pattern. This variety first arose in the 1950s as a cross between a Kohaku and an Asagi. The most commonly encountered Koromo is an Ai Goromo, which is coloured like a Kohaku, except that each of the scales within the red patches has a blue- or black-edge to it. Less common is the Budo-Goromo which has a darker (burgundy) hi overlay that gives it the appearance of bunches of grapes. Very rarely seen is the Tsumi-Goromo which is similar to Budo-Goromo, but the hi pattern is such a dark burgundy that it appears nearly black. A koi with coloured markings over a metallic base, or koi in two metallic colours.

Kikokuryū（輝黒竜, literally "Sparkle Black Dragon" or "Glitter Black Dragon"） A metallic skinned version of the Kumonryu.

Kin-Kikokuryū （金輝黒竜, literally "Gold Sparkle Black Dragon" or "Gold Glitter Black Dragon"）A metallic skinned version of the Kumonryu with a Kohaku-style hi pattern developed by Mr. Seiki Igarashi of Ojiya City. There are (at least) six different genetic sub-varieties of this general variety.

Ghost koi（人面魚、じんめんぎょ） - A hybrid of Ogon and wild carp with metallic scales. Considered by some to be not Nishikigoi.

Butterfly koi（鰭長錦鯉、ひれながにしきごい） - A hybrid of koi and Asian carp with long flowing fins. Various coloration depending on the koi stock used to hybrid. Considered by some to not be Nishikigoi.

Originated by cross breeding numerous different established varieties with "scale-less" German carp (generally, fish with only a single line of scales along each side of the dorsal fin). Also written as 独逸鯉. There are four main types of "Doitsu" scale patterns. The most common type (referred to above) have a row of scales beginning at the front of the dorsal fin and ending at the end of the dorsal fin (along both sides of the fin). The second type has a row of scales beginning where the head meets the shoulder and running the entire length of the fish (along both sides). The third type is the same as the second, with the addition of a line of (often quite large) scales running along the lateral line (along the side) of the fish, also referred to as "Mirror koi". The fourth (and rarest) type are referred to as "Armor koi" and are completely (or nearly) covered with very large scales that resemble plates of armor. Kagami-goi（鏡鯉、カガミゴイ, Mirror carp（ミラーカープ）.

Human Face Fish

The Human Face Fish is a cyprinid fish found in 2003 purported to have markings on its head reminiscent of the facial features of a human. It has been reported by Reuters as being a cross between two varieties of the carp ''Cyprinus carpio'', specifically the common carp and the leather carp, but by other news outlets as a true hybrid between the common carp and the ayu sweetfish ''Plecoglossus altivelis''. The latter is almost certainly incorrect though, as carps and ayu belong to quite different superorders of Teleostei.

The fish resides in a pond in Cheongju near Seoul, South Korea.

Differences from goldfish

Goldfish were developed in China more than a thousand years ago by selectively breeding Prussian carp for color mutations. By the Song Dynasty (960 – 1279), yellow, orange, white and red-and-white colorations had been developed. Goldfish (''Carassius auratus'') and Prussian carp (''Carassius gibelio'') are now considered different species. Goldfish were introduced to Japan in the 16th century and to Europe in the 17th century. Koi, on the other hand, were developed from common carp in Japan in the 1820s. Koi are domesticated common carp (''Cyprinus carpio'') that are culled for color, they are not a different species and will revert to the original coloration within a few generations if allowed to breed freely.

In general, goldfish tend to be smaller than koi, and have a greater variety of body shapes, and fin and tail configurations. Koi varieties tend to have a common body shape, but have a greater variety of coloration and color patterns. They also have prominent barbels on the lip. Some goldfish varieties, such as the common goldfish, comet goldfish and shubunkin have body shapes and coloration that are similar to koi, and can be difficult to tell apart from koi when immature. Since goldfish and koi were developed from different species of carp, even though they can interbreed, their offspring are sterile.

Keeping

The common carp is a hardy fish, and koi retain that durability. Koi are cold-water fish, but benefit from being kept in the 15-25 degrees C (59-77 degrees F) range and do not react well to long cold winter temperatures, their immune system 'turns off' below 10 degrees Celsius. Koi ponds usually have a meter or more of depth in areas of the world that become warm during the summer, whereas in areas that have harsher winters, ponds generally have a minimum of 1.5 meters (4½ feet). Specific pond construction has evolved by koi keepers intent on raising show quality koi.

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, otters, raccoons, cats, foxes, badgers and hedgehogs 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 watermelon. 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 them 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. Care should be taken by hobbyists that proper oxygenation and off-gassing occurs over the winter months in small water ponds so they do not perish. 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.

Koi can live for centuries. One famous scarlet koi, named "Hanako" (c. 1751 – July 7, 1977) was owned by several individuals, the last of whom was Dr. Komei Koshihara. Hanako was reportedly 226 years old upon her death. Her age was determined by removing one of her scales and examining it extensively in 1966.

Breeding

Like most fish, koi reproduce through spawning in which a female lays a vast number of eggs and one or more males fertilize them. Nurturing the resulting offspring (referred to as "fry") is a tricky and tedious job, usually done only by professionals. Although a koi breeder may carefully select the parents they wish based on their desired characteristics, the resulting fry will nonetheless exhibit a wide range of color and quality.

Koi will produce thousands of offspring from a single spawning. However, unlike cattle, purebred dogs, or more relevantly, goldfish, the large majority of these offspring, even from the best champion-grade koi, will not be acceptable as nishikigoi (they have no interesting colors) or may even be genetically defective. These unacceptable offspring are culled at various stages of development based on the breeder's expert eye and closely guarded trade techniques. Culled fry are usually destroyed or used as feeder fish (mostly used for feeding arowana due to the belief it will enhance its color), while older culls, within their first year between 3" to 6" long (also called "Tosai"), are often sold as lower-grade 'pond-quality' koi.

The semi-randomized result of the koi's reproductive process has both advantages and disadvantages for the breeder. While it requires diligent oversight to narrow down the favorable result that the breeder wants, it also makes possible the development of new varieties of koi within relatively few generations.

In the wild

Koi have been accidentally or deliberately released into the wild in every continent except Antarctica. They quickly revert to the natural coloration of common carp within a few generations. In many areas, they are considered an invasive species and pests. They greatly increase the turbidity of the water because they are constantly stirring up the substrate. This makes waterways unattractive, reduces the abundance of aquatic plants, and can render the water unsuitable for swimming or drinking, even by livestock. In some countries, koi have caused so much damage to waterways that vast amounts of money and effort have been spent trying to eradicate them, largely unsuccessfully.

See also

Aquaculture

Carp

Cyprinid

Goldfish

Koi pond

Culture of Japan

Japanese aesthetics

Notes

References

External links and further readings

Feature article on treating sick fish, especially koi, "Surgery to Scale", ''Cosmos Magazine''

Koi in the NIWA Atlas

Category:Carp Category:Cold-water aquarium fish Category:Introduced freshwater fish of New Zealand Category:Fish of East Asia Category:Fish of Bangladesh Category:Japanese words and phrases

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