Koi (鯉, English: /ˈkɔɪ/, Japanese: [koꜜi]) or more specifically jinli or nishikigoi (錦鯉, [ɲiɕi̥kiꜜɡoi], literally "brocaded carp"), are colored varieties of Amur carp (Cyprinus rubrofuscus) that are kept for decorative purposes in outdoor koi ponds or water gardens.
Koi is an informal group of the colored variants of C. carpio. Several varieties are recognized by the Japanese. Koi varieties are distinguished by coloration, patterning, and scalation. Some of the major colors are white, black, red, orange, 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.
Carp are a large group of fish originally found in Central Europe and Asia. Various carp species were originally domesticated in East Asia, where they were used as food fish. Carp are coldwater fish, and their ability 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. Carp were first bred for color mutations in China more than a thousand years ago, where selective breeding of the Prussian carp (Carassius gibelio) led to the development of the goldfish.
The Amur carp (Cyprinus rubrofuscus), a member of the cyprinid family species complex native to East Asia, was aquacultured as a food fish at least as long ago as the fifth century BC in China, and Jin Dynasty (fourth century AD) texts mentioned carp with various colors. The Amur carp was previously recognized as a subspecies of the common carp (as C. c. haematopterus), but recent authorities treat it as a separate species under the name C. rubrofuscus.
Amur carp were first bred for color in China in the first millennium and documented in at least three poems from Tang Dynasty to Qing dynasty, and in Japan in the 1820s, initially in the town of Ojiya in the Niigata Prefecture on the northeastern coast of Honshu island. The outside world was unaware of the development of color variations in Japanese koi until 1914, when the Niigata koi were exhibited at an annual exposition in Tokyo. From that time, interest in koi spread throughout Japan. From this original handful of koi, all other Nishikigoi varieties were bred, with the exception of the Ogon variety (single-colored, metallic koi), which was developed relatively recently.
The hobby of keeping koi eventually spread worldwide. They are now sold in many pet aquarium shops, with higher-quality fish available from specialist dealers. The collection of koi throughout the years has become quite the social hobby for many who have ponds. It is also common for hobbyists who are passionate about their koi to join a club specifically for their koi and ponds. Members tend to share their knowledge of the fish with others and even help each other out when they are in need of help with their koi.
Etymology The words "koi" and "nishikigoi" come from the Japanese reading of Classical Chinese words 鯉 (common carp) and 錦鯉 (brocaded carp) respectively. In both languages, the former can refer to many Asian carp species, including (and most commonly referring to) some invasive species in the United States. In Japanese, "koi" is a homophone for another word that means "affection" or "love", so koi are symbols of love and friendship in Japan. The first mention of the word "錦鯉" dates back to Tang Dynasty China: 錦鯉沖風擲，絲禽掠浪飛。短亭幽徑入，陳廟數峰圍。The "koi" plunged into the wind and the birds flew in the waves
In the past, koi were commonly believed to have been bred from the common carp (Cyprinus carpio). Extensive hybridization between different populations, coupled with widespread translocations, have muddled the historical zoogeography of the common carp and its relatives. Traditionally, Amur carp (C. rubrofuscus) were considered a subspecies of the common carp, often under the scientific name C. carpio haematopterus. However, they differ in meristics from the common carp of Europe and Western Asia, leading recent authorities to recognize them as a separate species, C. rubrofuscus (C. c. haematopterus being a junior synonym). Although one study of mitochondrial DNA (mtDNA) was unable to find a clear genetic structure matching the geographic populations (possibly because of translocation of carp from separate regions), others based on mtDNA, microsatellite DNA and genomic DNA found a clear separation between the European/West Asian population and the East Asian population, with koi belonging in the latter. Consequently, recent authorities have suggested that the ancestral species of the koi is C. rubrofuscus (syn. C. c. haematopterus) or at least an East Asian carp species instead of C. carpio Regardless, a taxonomic review of Cyprinus carp from eastern and southeastern Asia may be necessary, as the genetic variations do not fully match the currently recognized species pattern, with one study of mtDNA suggesting that koi are close to the Southeast Asian carp, but not necessarily the Chinese.
Koi varieties are distinguished by coloration, patterning, and scalation. Some of the major colors are white, black, red, yellow, blue, and cream. Although the possible colors are virtually limitless, breeders have identified and named a number of specific categories. The most notable 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 developed in the 1980s 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), also developed in the 1980s, 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:
Kōhaku (紅白) is 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). Taishō Sanshoku (or Taishō Sanke) (大正三色) is very similar to the kohaku, except for the addition of small black markings called sumi (墨). This variety was first exhibited in 1914 by the koi breeder Gonzo Hiroi, during the reign of the Taishō Emperor. In the United States, the name is often abbreviated to just "Sanke". The kanji, 三色, may be read as either sanshoku or as sanke (from its earlier name 三毛). Shōwa Sanshoku (or Showa Sanke) (昭和三色) is a black koi with red (hi 緋) and white (shiroji 白地) markings. The first Showa Sanke was exhibited in 1927, during the reign of the Shōwa 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. Tanchō (丹頂) is any koi with a solitary red patch on its head. The fish may be a Tanchō Shōwa, Tanchō Sanke, or even Tanchō Goshiki. It is named for the Japanese red-crowned crane (Grus japonensis), which also has a red spot on its head. Chagoi (茶鯉), "tea-colored", this koi can range 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. Asagi (浅黄) koi is light blue above and usually red below, 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 color, or indigo. Utsurimono (写り物) is a black koi with white, red, or yellow markings, in a zebra color pattern. The oldest attested form is the yellow form, called "black and yellow markings" (黒黄斑 Kuro ki madara) in the 19th century, but renamed Ki Utsuri (黄写り) by Elizaburo Hoshino, an early 20th-century koi breeder. The red and white versions are called Hi Utsuri (緋写り) and Shiro Utsuri (白写り) (piebald color morph), respectively. The word utsuri means to print (the black markings are reminiscent of ink stains). Genetically, it is the same as Showa, but lacking either red pigment (Shiro Utsuri) or white pigment (Hi Utsuri/Ki Utsuri). Bekko (鼈甲、べっ甲) is a white-, red-, or yellow-skinned koi with black markings sumi (墨). The Japanese name means "tortoise shell", and is commonly written as 鼈甲. The white, red, and yellow varieties are called Shiro Bekko (白), Aka Bekko (赤) and Ki Bekko (黄), respectively. It may be confused with the Utsuri. Goshiki (五色) is a dark koi with red (Kōhaku style) hi pattern. The Japanese name means "five colors". It appears similar to an Asagi, with little or no hi below the lateral line and a Kōhaku Hi pattern over reticulated (fishnet pattern) scales. The base color can range from nearly black to very pale, sky blue. 'Shūsui (秋翠) means "autumn green"; the Shūsui 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 Shūsui has 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. Kinginrin (金銀鱗) is a koi with metallic (glittering, metal-flake-appearing) scales. The name translates into English as "gold and silver scales"; it is often abbreviated to Ginrin. Ginrin versions of almost all other varieties of koi occur, and they are fashionable. Their sparkling, glittering scales contrast 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. Kawarimono (変わり物) is 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 in this one category. It is also known as kawarigoi (変わり鯉). Ōgon (黄金) is a metallic koi of one color only (hikarimono 光者). The most commonly encountered colors are gold, platinum, and orange. Cream specimens 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. Kumonryū (九紋竜)' （literally "nine tattooed dragons" 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 color with the seasons. Kumonryu compete in the Kawarimono category. Ochiba (落葉) is 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". Koromo (衣) is a white fish with a 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 colored like a Kohaku, except 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. Hikari-moyomono (光模樣者) is a koi with colored markings over a metallic base or in two metallic colors. Kikokuryū (輝黒竜, literally "sparkle" or "glitter black dragon") is a metallic-skinned version of the Kumonryu. Kin-Kikokuryū (金輝黒竜, literally "gold sparkle black dragon" or "gold glitter black dragon") is a metallic-skinned version of the Kumonryu with a Kohaku-style hi pattern developed by Mr. Seiki Igarashi of Ojiya City. At least six different genetic subvarieties of this general variety are seen. Ghost koi (人面魚、じんめんぎょ), a hybrid of Ogon and wild carp with metallic scales, is considered by some to be not nishikigoi. Butterfly koi (鰭長錦鯉、ひれながにしきごい) is a hybrid of koi and Asian carp with long flowing fins. Various colorations depend on the koi stock used to cross. It also is considered by some to not be nishikigoi. Doitsu-goi (ドイツ鯉) originated by crossbreeding numerous different established varieties with "scaleless" German carp (generally, fish with only a single line of scales along each side of the dorsal fin). Also written as 独逸鯉, four main types of Doitsu scale patterns exist. The most common type (referred to above) has 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 is referred to as "armor koi" and is completely (or nearly) covered with very large scales that resemble plates of armor. It also is called Kagami-goi (鏡鯉、カガミゴイ), or mirror carp (ミラーカープ).