, or more specifically , are colored varieties of carp (''

Cyprinus ''Cyprinus'' is the genus of typical carps in family Cyprinidae. Most species in the genus are of East Asia origin with only the common carp (''C. carpio'') in Western Asia and Europe; this invasive species has also been Introduced species, intr ...

'' sp.) that are kept for decorative purposes in outdoor

koi pond Koi ponds are ponds used for holding koi carp, usually as part of a garden. Koi ponds can be designed specifically to promote health and growth of the Nishikigoi or Japanese Ornamental Carp. Koi ponds or lakes are a traditional feature of Ja ...

s or

water garden Water garden or aquatic garden, is a term sometimes used for gardens, or parts of gardens, where any type of water feature (particularly garden ponds) is a principal or dominant element. The primary focus is on plants, but they will sometimes ...

s. Koi is an informal name for the colored variants of carp kept for ornamental purposes. There are many varieties of ornamental koi, originating from breeding that began in

Niigata, Japan is a prefecture in the Chūbu region of Honshu of Japan. Niigata Prefecture has a population of 2,131,009 (1 July 2023) and is the fifth-largest prefecture of Japan by geographic area at . Niigata Prefecture borders Toyama Prefecture and Naga ...

in the early 19th century.Japanese Ornamental Koi Carp: Origin, Variation and Genetics
May 2015 Several varieties are recognized by Japanese breeders and owners, distinguished by coloration, patterning, and scalation. Some of the major colors are white, black, red, orange, yellow, blue, brown and cream, besides metallic shades like gold and silver-white ('platinum') scales. The most popular category of koi is the ''Gosanke'', which is made up of the ''Kōhaku'', ''Taishō Sanshoku'' and ''Shōwa Sanshoku'' varieties.

History

Carp The term carp (: carp) is a generic common name for numerous species of freshwater fish from the family (biology), family Cyprinidae, a very large clade of ray-finned fish mostly native to Eurasia. While carp are prized game fish, quarries and a ...

are a large group of fish species originally native to

Central Europe Central Europe is a geographical region of Europe between Eastern Europe, Eastern, Southern Europe, Southern, Western Europe, Western and Northern Europe, Northern Europe. Central Europe is known for its cultural diversity; however, countries in ...

and

Asia Asia ( , ) is the largest continent in the world by both land area and population. It covers an area of more than 44 million square kilometres, about 30% of Earth's total land area and 8% of Earth's total surface area. The continent, which ...

. Various carp species were originally

domesticated Domestication is a multi-generational mutualistic relationship in which an animal species, such as humans or leafcutter ants, takes over control and care of another species, such as sheep or fungi, to obtain from them a steady supply of reso ...

China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

, where they were used primarily for consumption. Carp are

coldwater fish The term coldwater fish can have different meanings in different contexts. * In the context of fishkeeping, it refers to ornamental fish species that tolerate the temperatures of a typical indoor aquarium well and do not require a heater to rema ...

, 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.

Prehistory

In Japan,

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

fossils of the carp family (''Cyprinidae'') have been excavated from

Iki Island , or the , is an archipelago in the Tsushima Strait, which is administered as the city of Iki in Nagasaki Prefecture, Japan. The islands have a total area of with a total population of 28,008. Only four (4) of the twenty-three (23) named is ...

Nagasaki Prefecture is a Prefectures of Japan, prefecture of Japan, mainly located on the island of Kyūshū, although it also includes a number of islands off Kyūshū's northwest coast - including Tsushima and Iki. Nagasaki Prefecture has a population of 1,246,4 ...

. Furthermore, numerous carp

pharyngeal teeth Pharyngeal teeth are teeth in the pharyngeal arch of the throat of cyprinids, suckers, and a number of other fish species otherwise lacking teeth.Jomon and

Yayoi The Yayoi period (弥生時代, ''Yayoi jidai'') (c. 300 BC – 300 AD) is one of the major historical periods of the Japanese archipelago. It is generally defined as the era between the beginning of food production in Japan and the emergence o ...

period sites. For example, pharyngeal teeth of the extinct species ''Jōmon Koi'' (''Cyprinus sp.'') in addition to the modern species of carp (''

Cyprinus carpio The common carp (''Cyprinus carpio''), also known as European carp, Eurasian carp, or simply carp, is a widespread freshwater fish of eutrophic waters in lakes and large rivers in Europe and Asia.Fishbase''Cyprinus carpio'' Linnaeus, 1758/ref>Ark ...

'' or ''

Cyprinus rubrofuscus ''Cyprinus rubrofuscus'', the Amur carp, is a species of cyprinid fish, and is the wild form of the well-known koi. It is widespread in the fresh waters of eastern Asia, native to China, Korea, Russia, Vietnam and Laos from the Amur to Red Riv ...

'') have been excavated from the Akanoi Bay lakebed site () in

Lake Biwa is the largest freshwater lake in Japan. It is located entirely within Shiga Prefecture (west-central Honshu), northeast of the former capital city of Kyoto. Lake Biwa is an ancient lake, over 4 million years old. It is estimated to be the 13 ...

at the end of the Early Jomon Period (11,500 – 7,000 years ago). In addition, pharyngeal teeth of all six subfamilies of the Cyprinidae family living in Japan today, including carp (Cyprinus), have been found at the Awazu lakebed site () dating from the Middle Jomon Period (5500 – 4400 years ago). There are differences in the length distribution of carp excavated from Jomon and Yayoi sites, as estimated from the size of their pharyngeal teeth. Specifically, not only adult carp but also juvenile carp (less than 150 mm in length) have been found at the Yayoi site. This difference is thought to be because the Jomon only collected carp from lakes and rivers, while the Yayoi cultivated primitive carp along with the spread of rice paddies. It was previously thought that all Japanese carp were introduced from China in prehistoric times. However, recent analysis of

mitochondrial DNA Mitochondrial DNA (mtDNA and mDNA) is the DNA located in the mitochondrion, mitochondria organelles in a eukaryotic cell that converts chemical energy from food into adenosine triphosphate (ATP). Mitochondrial DNA is a small portion of the D ...

revealed a significant evolutionary divergence (phylogenetic split) within common carp Cyprinus carpio between the native wild form found in Lake Biwa and the Eurasian wild form, along with domesticated varieties. This supports the idea of the ancient origin of the native Japanese form (Cyprinus sp.), as well as the East Asian ancient lineage of wild common carp (C. carpio), previously proposed on the basis of fossil data. However, it is unknown when the carp from the continent was introduced to Japan. In addition, a possible multiple origin of koi carp was indicated by the polyphyletic distribution of five mtDNA haplotypes of koi carp within the ‘Eurasian’ clade. Moreover, the oldest record of the introduction of non-native fish in Japan is that of goldfish from China (1502 or 1602), and there is no record of carp (including colored carp) until the introduction of the

mirror carp The common carp (''Cyprinus carpio''), also known as European carp, Eurasian carp, or simply carp, is a widespread freshwater fish of eutrophic waters in lakes and large rivers in Europe and Asia.Fishbase''Cyprinus carpio'' Linnaeus, 1758/ref>Ark ...

, called ''Doitsugoi'' (German carp), in 1904.

Middle Ages

In the Japanese history book ''

Nihon Shoki The or , sometimes translated as ''The Chronicles of Japan'', is the second-oldest book of classical Japanese history. It is more elaborate and detailed than the , the oldest, and has proven to be an important tool for historians and archaeol ...

'' (Chronicles of Japan, 720), it is written that

Emperor Keikō , also known as and , was the 12th legendary Emperor of Japan, according to the traditional order of succession. Both the ''Kojiki'', and the ''Nihon Shoki'' (collectively known as the ''Kiki'') record events that took place during Keikō's all ...

released carp in a pond for viewing when he visited

Mino Province was a province of Japan in the area of Japan that is today southern Gifu Prefecture. Mino was bordered by Ōmi to the west, Echizen and Hida to the north, Shinano to the east, and Ise, Mikawa, and Owari to the south. Its abbreviated fo ...

(present

Gifu Prefecture is a Prefectures of Japan, prefecture of Japan located in the Chūbu region of Honshu. Gifu Prefecture has a population of 1,910,511 () and has a geographic area of . Gifu Prefecture borders Toyama Prefecture to the north; Ishikawa Prefecture ...

) in the fourth year of his reign (74 AD). In Cui Bao's ''Gǔjīnzhù'' (, Annotations on the Ancient and Modern Period) from the

Western Jin Dynasty Western may refer to: Places *Western, Nebraska, a village in the US * Western, New York, a town in the US * Western Creek, Tasmania, a locality in Australia * Western Junction, Tasmania, a locality in Australia *Western world, countries that ...

(4th century A.D.) in China, carp of the following colors are described: red horse (), blue horse (), black horse (), white horse (), and yellow pheasant (). In China in those days, carp were called horses because they were believed to be the vehicles of hermits and to run in the sky. Japan's oldest drug dictionary, Fukane Sukehito's '' Honzō Wamyō'' (, 918) mentions red carp (), blue carp (), black carp (), white carp (), and yellow carp () as Japanese names corresponding to the above Chinese names, suggesting that carp of these colors existed in China and Japan in those days. In addition, Hitomi Hitsudai's drug dictionary ''Honchō Shokkan'' (, Japanese Medicine Encyclopedia, 1697) states that red, yellow, and white carp of the three colors were in Japan at that time. However, it is believed that these single-colored carp were not a variety created by

artificial selection Selective breeding (also called artificial selection) is the process by which humans use animal breeding and plant breeding to selectively develop particular phenotypic traits (characteristics) by choosing which typically animal or plant ...

, as is the case with today's koi, but rather a mutation-induced color change. In ancient times, carp was farmed primarily for food. Mutational color variation in carp is relatively common in nature, but is not suitable for development alongside farming for food in poor rural communities; color inheritance is unstable and selection to maintain color variation is costly. For example, in current-day farming of koi as ornamental fish, the percentage of superior colored fish to the number of spawn is less than 1%. The Amur carp (''

'') is a member of the cyprinid family

species complex In biology, a species complex is a group of closely related organisms that are so similar in appearance and other features that the boundaries between them are often unclear. The taxa in the complex may be able to hybridize readily with each oth ...

native to

East Asia East Asia is a geocultural region of Asia. It includes China, Japan, Mongolia, North Korea, South Korea, and Taiwan, plus two special administrative regions of China, Hong Kong and Macau. The economies of Economy of China, China, Economy of Ja ...

. Amur carp were previously identified 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 have been

aquaculture Aquaculture (less commonly spelled aquiculture), also known as aquafarming, is the controlled cultivation ("farming") of aquatic organisms such as fish, crustaceans, mollusks, algae and other organisms of value such as aquatic plants (e.g. Nelu ...

d as a food fish at least as long ago as the fifth century BC in China.

Modern period

The systematic breeding of ornamental Amur carp began in the 1820s in an area known as "Nijūmuragō" (, ) which spans Ojiya and Yamakoshi in

Niigata Prefecture is a Prefectures of Japan, prefecture in the Chūbu region of Honshu of Japan. Niigata Prefecture has a population of 2,131,009 (1 July 2023) and is the List of Japanese prefectures by area, fifth-largest prefecture of Japan by geographic area ...

(located on the northeastern coast of

Honshu , historically known as , is the largest of the four main islands of Japan. It lies between the Pacific Ocean (east) and the Sea of Japan (west). It is the list of islands by area, seventh-largest island in the world, and the list of islands by ...

) in Japan. In Niigata Prefecture, Amur carp were farmed for food in Musubu Shinden, Kanbara County (present Akiba Ward,

Niigata City is a city located in the northern part of Niigata Prefecture (). It is the capital and the most populous city of Niigata Prefecture, and one of the cities designated by government ordinance of Japan, located in the Chūbu region of Japan. It is ...

) from the end of the

Genna was a coming after ''Keichō'' and before ''Kan'ei.'' This period spanned the years from July 1615 to February 1624. The reigning emperor was . It is also known as ''Genwa''. Change of era * 1615 : The era name was changed to mark the enthr ...

era (1615–1624). In the Nijūmuragō area, carp were also farmed in terraced ponds near terraced rice paddies by 1781 at the latest, but the ponds ran dry due to a severe drought that occurred around that time, and the carp escaped the disaster by taking refuge in ponds on the grounds of Senryu Shrine in Higashiyama Village and Juni Shrine in Higashitakezawa Village. During the

Bunka was a after '' Kyōwa'' and before ''Bunsei''. The period spanned the years from January 1804 to April 1818. The reigning emperors were and . Change of era * February 11, 1804 (): The new era name of ''Bunka'' ( meaning "Culture" or "Civili ...

and

Bunsei was a after '' Bunka'' and before ''Tenpō''. This period spanned the years from April 1818 through December 1830. The reigning emperor was . Change of era * April 22, 1818 (): The new era name was created to mark the enthronement of the emp ...

eras (1804 – 1830), people in the Nijūmuragō area bred red and white koi in addition to black koi, and crossed them to produce red and white colored koi. After that, they further crossed them and perfected them. Around 1875, colored koi became popular and the number of breeders increased, and some expensive koi were produced, but Niigata Prefecture banned the aquaculture of ornamental koi because it was considered a speculative business, and the business suffered a major blow for a time. However, the ban was lifted soon after, thanks to the petition of the villagers. At that time, colored koi included ''Kōhaku'', ''Asagi'', ''Ki Utsuri'', etc. From this original handful of koi varieties, all other Nishikigoi varieties were bred, with the exception of the Ogon variety (single-colored, metallic koi), which was developed relatively recently. Koi breeding flourished in the Nijūmuragō area for two reasons: 1) the custom of raising koi in fallow fields for emergency food during the winter, and 2) the existence of many ''inden'' (), or hidden rice fields in the mountains, unknown to the lord, which allowed the farmers to avoid taxes and become relatively wealthy. Breeding of koi was promoted as a hobby of farmers who could afford it, and high-quality individuals came to be bought and sold. The name ''Nishikigoi'' (brocaded carp) did not exist until the 1910s. Before that time, ''Nishikigoi'' were called ''Madaragoi'' (, ), ''Kawarigoi'' (, ), ''Irogoi'' (, ), ''Moyōgoi'' (, ), and so on. A geographical book on

Suruga Province was an Provinces of Japan, old province in the area that is today the central part of Shizuoka Prefecture. Suruga bordered on Izu Province, Izu, Kai Province, Kai, Sagami Province, Sagami, Shinano Province, Shinano, and Tōtōmi Province, Tōtōm ...

(present-day

Shizuoka Prefecture is a Prefectures of Japan, prefecture of Japan located in the Chūbu region of Honshu. Shizuoka Prefecture has a population of 3,555,818 and has a geographic area of . Shizuoka Prefecture borders Kanagawa Prefecture to the east, Yamanashi Pref ...

), Abe Masanobu's ''Sunkoku Zasshi'' (1843), mentions that in addition to Asagi, purple, red, and white carp, there are "spotted carp (also known as Bekko carp)." This probably refers to two- or three-colored carp caused by mutation, and is a valuable record of ''Nishikigoi'' of the

Edo period The , also known as the , is the period between 1600 or 1603 and 1868 in the history of Japan, when the country was under the rule of the Tokugawa shogunate and some 300 regional ''daimyo'', or feudal lords. Emerging from the chaos of the Sengok ...

(1603 – 1868). Sanshoku goi

In 1900, there was a three-colored carp in

Ritsurin Garden is a large, historic garden in Takamatsu, Japan. It was completed in 1745 as a private strolling garden and villa for the local feudal lords, and opened to the public in 1875. Ritsurin is one of the largest strolling gardens in Japan, and a ma ...

Takamatsu file:Takamatsu City Hall.jpg, 270px, Takamatsu City Hall file:Takamatsu city center area Aerial photograph.2007.jpg, 270px, Aerial view of Takamatsu city center file:Takamatsu200910cut.JPG, 270px, View from Yashima to Takashima port is a capital ...

Kagawa Prefecture is a Prefectures of Japan, prefecture of Japan located on the island of Shikoku. Kagawa Prefecture has a population of 949,358 (as of 2020) and is the List of Japanese prefectures by area, smallest prefecture by geographic area at . Kagawa Pr ...

, and the price was over 1,000 yen per fish, which was a high price for that time. The three-colored carp had a red belly and ''asagi'' (light blue) back with black spots, and is thought to have been a mutation similar to today's ''Asagi'' koi. Odd-eyed cat and Koi

The magazine "Shonen" (1910) introduced ''Nishikigoi'' under the name of ''Madaragoi'' (spotted carp) or ''Kawarigoi'' (variant carp), and said that even skilled fish breeders did not know how they could produce ''Nishikigoi'', but only waited for them to be produced by chance. The price of ''Nishikigoi'' at a fish show in

Fukagawa In Japan, Fukagawa (深川) may refer to: * Fukagawa, Hokkaidō, a city ** Fukagawa Station, a railway station * Fukagawa, Tokyo is a district in Kōtō, Tokyo. It is traditionally part of the area of Tokyo. Formerly, it was a ward of the his ...

, Tokyo, was 100 to 150 yen per fish, which was "extremely expensive" at the time. Therefore, even at that time, mutant ''Nishikigoi'' were known to some fish breeders and hobbyists in Tokyo, but artificial breeds such as Nijūmuragō's ''Nishikigoi'' were still unknown to the general public. In 1914, when the Tokyo Taishō Exposition was held, the "Koi Exhibit Association" was formed mainly by koi breeders in Higashiyama and Takezawa villages, and koi were exhibited. At the time, they were still called "colored carp" or "patterned carp," and they were described as "the first of their kind ever seen in the Tokyo area." And the koi received much attention, winning a silver medal. After the exposition closed, they presented eight koi to the Crown Prince (

Emperor Showa , posthumously honored as , was the 124th emperor of Japan according to the traditional order of succession, from 25 December 1926 until his death in 1989. He remains Japan's longest-reigning emperor as well as one of the world's longest-rei ...

). This exhibition triggered an expansion of sales channels, and the market value of koi soared. In 1917, the ''Taishō Sanshoku'' (by Eizaburo Hoshino) was fixed as a breed. The name ''Nishikigoi'' is said to have been given by Kei Abe, who was the chief fisheries officer of the Niigata Prefectural Government in the Taisho era (1912–1926), after he admired the ''Taishō Sanshoku'' when he first saw it. In 1917, the fixation of ''Kōhaku'' (by Kunizo Hiroi), which had first been produced in the 1880s, was also assured. Apart from the koi of Niigata Prefecture's Nijūmuragō area, there is a variety called ''Shūsui'' (), which was created by Tokyo-based goldfish breeder Kichigoro Akiyama in 1906 by crossing a female

leather carp ''Cyprinus carpio carpio'' is a subspecies of the common carp that is commonly found in Europe. They are native to much of Europe (notably the Danube and Volga Rivers) and can also be found in the Caucasus and Central Asia. Mitochondrial DNA ana ...

imported from Germany with a male Japanese ''Asagi'' or spotted carp. The leather carp is a low scaled variety bred in 1782 in Austria, and was sent to Japan from Munich, Germany in 1904, along with the mirror carp, which also has few scales. In Japan, these two varieties are called ''Doitsugoi'' (German carp), and ''Shūsui'' and its lineage are also called ''Doitsu'' or ''Doitsugoi'' in koi. In 1927, ''Shōwa Sanshoku'' (by Shigekichi Hoshino) was fixed as a breed, and in 1939, koi were exhibited at the Japanese pavilion at the

Golden Gate International Exposition The Golden Gate International Exposition (GGIE) was a World's Fair held at Treasure Island in San Francisco, California, U.S. The exposition operated from February 18, 1939, through October 29, 1939, and from May 25, 1940, through September 29, ...

held in San Francisco.

Today

The hobby of keeping koi eventually spread worldwide. They are sold in many pet aquarium shops, with higher-quality fish available from specialist dealers. Collecting koi has become a social hobby. Passionate hobbyists join clubs, share their knowledge and help each other with their koi. In particular, since the 21st century, some wealthy Chinese have imported large quantities of koi from Niigata in Japan, and the price of high-quality carp has soared. In 2018, one carp was bought by a Chinese collector for about $2 million, the highest price ever. There are also cases in which purchased carp are bred in China and sold to foreign countries, and many breeds are spreading all over the world.

Etymology

The words "koi" and "nishikigoi" come from the Japanese words 鯉 (carp), and 錦鯉 (brocaded carp), respectively. In Japanese, "koi" is a

homophone A homophone () is a word that is pronounced the same as another word but differs in meaning or in spelling. The two words may be spelled the same, for example ''rose'' (flower) and ''rose'' (past tense of "rise"), or spelled differently, a ...

for 恋, another word that means "affection" or "love", so koi are symbols of love and friendship in Japan. Colored ornamental carp were originally called ''Irokoi'' (色鯉) meaning colored carp, ''Hanakoi'' (花鯉) meaning floral carp, and ''Moyōkoi'' (模様鯉) meaning patterned carp. There are various theories as to how these words came to be disused, in favor of ''Nishikigoi'' (錦鯉), which is used today. One theory holds that, during

World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

, the words ''Irokoi'' and ''Hanakoi'' (which can have sexual meanings) were changed to ''Nishikigoi'' because they were not suitable for the social situation of war. Another theory is that'' Nishikigoi'', which was the original name for the popular Taishō Sanshoku variety, gradually became the term used for all ornamental koi.The History of Nishikigoi 錦鯉とその起源
Zen Nippon Airinkai

Taxonomy

Cyprinus melanotus and Cyprinus conirostris

The koi are a group of breeds produced by artificial selection primarily from black carp called '' nogoi'' (, ) or ''magoi'' (, ), which inhabit lakes, ponds, and rivers in Japan. The black carp refers to the

Eurasian carp The common carp (''Cyprinus carpio''), also known as European carp, Eurasian carp, or simply carp, is a widespread freshwater fish of eutrophic waters in lakes and large rivers in Europe and Asia.Fishbase''Cyprinus carpio'' Linnaeus, 1758/ref>Ark ...

(''Cyprinus carpio''), which was previously thought to have been introduced to Japan from Eurasia in prehistoric times.

Philipp Franz von Siebold Philipp Franz Balthasar von Siebold (17 February 1796 – 18 October 1866) was a German physician, botanist and traveller. He achieved prominence by his studies of Japanese flora (plants), flora and fauna (animals), fauna and the introduction of ...

of the Netherlands, who stayed in Japan during the Edo period, reported in ''

Fauna Japonica ''Fauna Japonica'' is a series of monographs on the zoology of Japan. It was the first book written in a European language ( French) on the Japanese fauna, and published serially in five volumes between 1833 and 1850. The full title is . Based ...

'' (1833–1850) that there were three species of carp in Japan: ''Cyprinus haematopterus'', ''Cyprinus melanotus'', and ''Cyprinus conirostris''. This classification has not received much attention until recently, and it was thought that only one species of carp existed in Japan. However, recent analysis of mitochondrial DNA has revealed that there are at least two species of carp in Japan: native carp and carp from Eurasia. Currently, the Japanese native carp is assumed to be ''Cyprinus melanotus'', and a new scientific name for it is being considered. ''Cyprinus haematopterus'' is thought to refer to the Amur carp of Eurasian origin, traditionally called ''Yamatogoi'' (, ) in Japan. ''Yamatogoi'' have been famous since the Edo period as farmed carp in

Yamato Province was a province of Japan, located in Kinai, corresponding to present-day Nara Prefecture in Honshū. Nussbaum, Louis-Frédéric (2005). "Yamato" in . It was also called . Yamato consists of two characters, 大 "great", and 和 " Wa". At first, th ...

(now

Nara Prefecture is a Prefectures of Japan, prefecture of Japan located in the Kansai region of Honshu. Nara Prefecture has a population of 1,321,805 and has a geographic area of . Nara Prefecture borders Kyoto Prefecture to the north, Osaka Prefecture to the ...

). Other carp of the same type as ''Yamatogoi'' are known as ''Yodogoi'' (,

Yodo River The , also called the Seta River (瀬田川 ''Seta-gawa'') and the Uji River (宇治川 ''Uji-gawa'') at portions of its route, is the principal river in Osaka Prefecture on Honshu, Japan. The source of the river is Lake Biwa in Shiga Prefectur ...

carp) from

Osaka is a Cities designated by government ordinance of Japan, designated city in the Kansai region of Honshu in Japan. It is the capital of and most populous city in Osaka Prefecture, and the List of cities in Japan, third-most populous city in J ...

and ''Shinshūgoi'' (, introduced ''Yodogoi'') from

Nagano Prefecture is a Landlocked country, landlocked Prefectures of Japan, prefecture of Japan located in the Chūbu region of Honshu. Nagano Prefecture has a population of 2,007,682 () and has a geographic area of . Nagano Prefecture borders Niigata Prefecture ...

. These carp were famous for their delicious taste. Since the Meiji period, ''Yamatogoi'' have been released into lakes and rivers throughout Japan, causing genetic contamination with native carp and making research on the origin of the Japanese carp difficult. Koi is thought to be primarily of this ''Yamatogoi'' (Amur carp) lineage, but it also carries some genes of the native Japanese carp. In the past, koi were commonly believed to have been bred from the

common carp The common carp (''Cyprinus carpio''), also known as European carp, Eurasian carp, or simply carp, is a widespread freshwater fish of eutrophic waters in lakes and large rivers in Europe and Asia.Fishbase''Cyprinus carpio'' Linnaeus, 1758/ref>Ark ...

(''Cyprinus carpio''). Extensive hybridization between different populations, coupled with widespread translocations, has muddled the historical

zoogeography Zoogeography is the branch of the science of biogeography that is concerned with geographic distribution (present and past) of animal species. As a multifaceted field of study, zoogeography incorporates methods of molecular biology, genetics, mo ...

of the common carp and its relatives. Traditionally, Amur carp (''C. rubrofuscus'') were considered a

subspecies In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...

of the common carp, often under the scientific name ''C. carpio haematopterus''. However, they differ in

meristics Meristics is an area of zoology and botany which relates to counting quantitative features of animals and plants, such as the number of fins or scales in fish. A meristic (countable trait) can be used to describe a particular species, or used to i ...

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 In taxonomy, the scientific classification of living organisms, a synonym is an alternative scientific name for the accepted scientific name of a taxon. The botanical and zoological codes of nomenclature treat the concept of synonymy differently. ...

). Although one study of

(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 A microsatellite is a tract of repetitive DNA in which certain Sequence motif, DNA motifs (ranging in length from one to six or more base pairs) are repeated, typically 5–50 times. Microsatellites occur at thousands of locations within an organ ...

DNA and

genomic DNA Genomic deoxyribonucleic acid (abbreviated as gDNA) is chromosomal DNA, in contrast to extra-chromosomal DNAs like plasmids. Most organisms have the same genomic DNA in every cell; however, only certain genes are active in each cell to allow for c ...

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 280px, Generalized scheme of taxonomy Taxonomy is a practice and science concerned with classification or categorization. Typically, there are two parts to it: the development of an underlying scheme of classes (a taxonomy) and the allocation ...

review of ''

'' 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.

Varieties

According to ''Zen Nippon Airinkai'', a group that leads the breeding and dissemination of koi in Japan, there are more than 100 varieties of koi created through breeding, and each variety is classified into 16 groups.The Varieties of Nishikigoi
Zen Nippon Airinkai Koi varieties are distinguished by coloration, patterning, and scalation. Some of the major colors are white, black, red, yellow, blue, and cream. Metallic shades of gold and platinum in the scales have also been developed through selective breeding. Although the possible colors are virtually limitless, breeders have identified and named a number of specific categories. The most notable category is , which is made up of the ''Kōhaku'', ''Taishō Sanshoku'', and ''Shōwa Sanshoku'' varieties. New koi varieties are still being actively developed. Ghost koi developed in the 1980s have become very popular in the

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Northwestern Europe, off the coast of European mainland, the continental mainland. It comprises England, Scotlan ...

; they are a

hybrid Hybrid may refer to: Science * Hybrid (biology), an offspring resulting from cross-breeding ** Hybrid grape, grape varieties produced by cross-breeding two ''Vitis'' species ** Hybridity, the property of a hybrid plant which is a union of two diff ...

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: * is a white-skinned koi, with large red markings on the top. The name means "red and white"; ''kōhaku'' was one of the first ornamental varieties to be established in Japan (late 19th century). * is very similar to the ''kōhaku'', 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 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). * is a black koi with red (''hi'' 緋) and white (''shiroji'' 白地) markings. The first ''Shōwa Sanke'' was exhibited in 1927, during the reign of the Shōwa Emperor. In America, the name is often abbreviated to just "Shōwa". The amount of ''shiroji'' on ''Shōwa Sanke'' has increased in modern times (''Kindai Shōwa'' 近代昭和), to the point that it can be difficult to distinguish from ''Taishō Sanke''. The ''kanji'', 三色, may be read as either ''sanshoku'' or as ''sanke.'' * is a white-, red-, or yellow-skinned koi with black markings . The Japanese name means "tortoise shell", and is commonly written as 鼈甲. The white, red, and yellow varieties are called , and , respectively. It may be confused with the ''Utsuri''. * is a black koi with white, red, or yellow markings, in a

zebra Zebras (, ) (subgenus ''Hippotigris'') are African equines with distinctive black-and-white striped coats. There are three living species: Grévy's zebra (''Equus grevyi''), the plains zebra (''E. quagga''), and the mountain zebra (''E. ...

color pattern. 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 (piebald color morph), respectively. The word ''utsuri'' means to print (the black markings are reminiscent of ink stains). Genetically, it is the same as ''Shōwa'', but lacking either red pigment (''Shiro Utsuri'') or white pigment (''Hi Utsuri''/''Ki Utsuri''). * 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 Scallions (also known as green onions and spring onions) are edible vegetables of various species in the genus ''Allium''. Scallions generally have a milder taste than most onions. Their close relatives include garlic, shallots, leeks, chive ...

color, or

indigo InterGlobe Aviation Limited (d/b/a IndiGo), is an India, Indian airline headquartered in Gurgaon, Haryana, India. It is the largest List of airlines of India, airline in India by passengers carried and fleet size, with a 64.1% domestic market ...

. * ' means "autumn green"; the ''Shūsui'' was created in 1910 by Yoshigoro Akiyama（秋山　吉五郎, by crossing Japanese ''Asagi'' with German

. 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 Sky blue refers to a collection of shades comparable to that of a clear daytime sky. Typically it is a shade of cyan or light teal, though some iterations are closer to light azure or light blue. The term (as "sky blew") is attested from 1681 ...

/gray color above the lateral line and red or orange (and very, very rarely bright yellow) below the lateral line and on the cheeks. * is a white fish with a ''Kōhaku''-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 ''Kōhaku'' and an ''Asagi''. The most commonly encountered ''Koromo'' is an , which is colored like a ''Kōhaku'', except each of the scales within the red patches has a blue or black edge to it. Less common is the , which has a darker (burgundy) ''hi'' overlay that gives it the appearance of bunches of grapes. Very rarely seen is the , which is similar to ''Budō-Goromo'', but the ''hi'' pattern is such a dark burgundy that it appears nearly black. * 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 . * 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. * is a variety of which the whole body is one color and the body is shiny, and it is called differently depending on the color. * is a koi with colored markings over a metallic base or in two metallic colors. * is a cross between ''utsurimono'' series and ''Ōgon''. * 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. * 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 The red-crowned crane (''Grus japonensis''), also called the Manchurian crane (; the Chinese character '丹' means 'red', '頂/顶' means 'crown (anatomy), crown' and '鶴/鹤' means 'crane'), is a large East Asian Crane (bird), crane among the ...

(''Grus japonensis''), which also has a red spot on its head. * , "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. * 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. * ' （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. * 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". * ''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 ''Kōhaku''-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''. * originated by crossbreeding numerous different established varieties with "scaleless"

German carp The common carp (''Cyprinus carpio''), also known as European carp, Eurasian carp, or simply carp, is a widespread freshwater fish of eutrophic waters in lakes and large rivers in Europe and Asia.Fishbase''Cyprinus carpio'' Linnaeus, 1758/ref>Ark ...

(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). File:Kohaku.jpg, Kōhaku File:Tanchosanke.JPG, Tanchō Sanke File:Showa4.JPG, Shōwa Sanke File:Koi asagi.jpg, Asagi File:AZBG_Koi.jpg, Bekkō File:Gin Rin Showa.jpg, Gin Rin Shōwa

Differences from goldfish

Goldfish The goldfish (''Carassius auratus'') is a freshwater fish in the family Cyprinidae of the order Cypriniformes. It is commonly kept as a pet in indoor aquariums, and is one of the most popular aquarium fish. Goldfish released into the w ...

(''Carassius auratus'') were developed in

more than a thousand years ago by

selectively breeding Selective breeding (also called artificial selection) is the process by which humans use animal breeding and plant breeding to selectively develop particular phenotypic traits (characteristics) by choosing which typically animal or plant ma ...

colored varieties; by the

Song dynasty The Song dynasty ( ) was an Dynasties of China, imperial dynasty of China that ruled from 960 to 1279. The dynasty was founded by Emperor Taizu of Song, who usurped the throne of the Later Zhou dynasty and went on to conquer the rest of the Fiv ...

(960–1279), yellow, orange, white, and red-and-white colorations had been developed. Goldfish were introduced to Japan in the 16th century and to Europe in the 17th century. On the other hand, most ornamental koi breeds currently distributed worldwide originate from Amur carp (''Cyprinus rubrofuscus'') bred in Japan in the first half of the 19th century. Koi are domesticated Amur carp that are selected or 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. Some goldfish varieties, such as the

common goldfish The common goldfish is a breed of goldfish and a family of Cyprinidae in the order cypriniformes. Goldfish are descendants of wild carp from East Asia. Most varieties of fancy goldfish were derived from this simple breed. Common goldfish com ...

comet goldfish The comet or comet-tailed goldfish is a single-tailed goldfish bred in the United States. It is similar to the common goldfish, except slightly smaller and slimmer, and is mainly distinguished by its long deeply forked tail. Comet goldfish tend ...

, and shubunkin, have body shapes and coloration that are similar to koi, and can be difficult to tell apart from koi when immature. Goldfish and koi can interbreed; however, as they were developed from different species of carp, their offspring are sterile.

Health, maintenance, and longevity

The Amur carp is a hardy fish, and koi retain that durability. Koi are coldwater fish, but benefit from being kept in the range, and do not react well to long, cold, winter temperatures; their immune systems are very weak below . Koi ponds usually have a metre 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 . Specific pond construction has been evolved by koi keepers intent on raising show-quality koi. The bright colors of koi put them at a severe disadvantage against predators; a white-skinned ''Kōhaku'' is highly noticeable against the dark green of a pond.

Heron Herons are long-legged, long-necked, freshwater and coastal birds in the family Ardeidae, with 75 recognised species, some of which are referred to as egrets or bitterns rather than herons. Members of the genus ''Botaurus'' are referred to as bi ...

kingfisher Kingfishers are a family, the Alcedinidae, of small to medium-sized, brightly coloured birds in the order Coraciiformes. They have a cosmopolitan distribution, with most species living in the tropical regions of Africa, Asia, and Oceania, ...

otter Otters are carnivorous mammals in the subfamily Lutrinae. The 13 extant otter species are all semiaquatic, aquatic, or marine. Lutrinae is a branch of the Mustelidae family, which includes weasels, badgers, mink, and wolverines, among ...

raccoon The raccoon ( or , ''Procyon lotor''), sometimes called the North American, northern or common raccoon (also spelled racoon) to distinguish it from Procyonina, other species of raccoon, is a mammal native to North America. It is the largest ...

skunk Skunks are mammals in the family Mephitidae. They are known for their ability to spray a liquid with a strong, unpleasant scent from their anal glands. Different species of skunk vary in appearance from black-and-white to brown, cream or gi ...

mink Mink are dark-colored, semiaquatic, carnivorous mammals of the genera ''Neogale'' and '' Mustela'' and part of the family Mustelidae, which also includes weasels, otters, and ferrets. There are two extant species referred to as "mink": the A ...

cat The cat (''Felis catus''), also referred to as the domestic cat or house cat, is a small domesticated carnivorous mammal. It is the only domesticated species of the family Felidae. Advances in archaeology and genetics have shown that the ...

fox Foxes are small-to-medium-sized omnivorous mammals belonging to several genera of the family Canidae. They have a flattened skull; upright, triangular ears; a pointed, slightly upturned snout; and a long, bushy tail ("brush"). Twelve species ...

es, and

badgers Badgers are medium-sized short-legged omnivores in the superfamily Musteloidea. Badgers are a polyphyletic rather than a natural taxonomic grouping, being united by their squat bodies and adaptions for fossorial activity rather than by their ...

are all capable of spotting out koi and eating them. A well-designed outdoor pond has areas too deep for herons to stand, overhangs high enough above the water that mammals cannot 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 A pump is a device that moves fluids (liquids or gases), or sometimes Slurry, slurries, by mechanical action, typically converted from electrical energy into hydraulic or pneumatic energy. Mechanical pumps serve in a wide range of application ...

and a

filtration Filtration is a physical separation process that separates solid matter and fluid from a mixture using a ''filter medium'' that has a complex structure through which only the fluid can pass. Solid particles that cannot pass through the filte ...

system to keep the water clear. Koi are an omnivorous fish. They 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, koi can be checked for parasites and ulcers. Naturally, koi are bottom feeders with a mouth configuration adapted for that. Some koi have a tendency to eat mostly from the bottom, so food producers create a mixed sinking and floating combination food. Koi recognize the persons 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 systems slow nearly to a halt, and they eat very little, perhaps no more than nibbles of algae from the bottom. Feeding is not recommended when the water temperature drops below . Care should be taken by hobbyists that proper oxygenation, pH stabilization, and off-gassing occur over the winter in small ponds. Their appetites do not come back until the water becomes warm in the spring. Koi have been reported to achieve ages of 100–200 years. One famous scarlet koi named " Hanako" was owned by several individuals, the last of whom was Komei Koshihara. In July 1974, a study of the

growth rings Dendrochronology (or tree-ring dating) is the scientific method of chronological dating, dating tree rings (also called growth rings) to the exact year they were formed in a tree. As well as dating them, this can give data for dendroclimatology, ...

of one of the koi's scales reported that Hanako was 226 years old. Some sources give an accepted age for the species at little more than 50 years.

Disease

Koi are very hardy. With proper care, they resist many of the parasites that affect more sensitive tropical fish species, such as ''

Trichodina Trichodina is a genus of ciliate alveolates that is ectocommensal or parasitic on aquatic animals, particularly fish. They are characterised by the presence of a ring of interlocking cytoskeletal denticles, which provide support for the cell ...

, Epistylis'', and ''

Ichthyophthirius multifiliis ''Ichthyophthirius multifiliis'', often termed "Ich", is a parasitic ciliate described by the French Parasitology, parasitologist Fouquet in 1876. Only one species is found in the genus which also gave name to the family. The name literally tran ...

'' infections. Water changes help reduce the risk of diseases and keep koi from being stressed. Two of the biggest health concerns among koi breeders are the koi herpes virus (KHV) and

rhabdovirus ''Rhabdoviridae'' is a family of negative-strand RNA viruses in the order ''Mononegavirales''. Vertebrates (including mammals and humans), invertebrates, plants, fungi and protozoans serve as natural hosts. Diseases associated with member virus ...

carpio, which causes

spring viraemia of carp Spring viraemia of carp, also known as swim bladder inflammation, is caused by Spring viremia of carp virus (''Sprivivirus cyprinus''). It is listed as a notifiable disease under the World Organisation for Animal Health. Impacted species Spring ...

(SVC). No treatment is known for either disease. Some koi farms in Israel use the KV3 vaccine, developed by M. Kotler from the

Hebrew University of Jerusalem The Hebrew University of Jerusalem (HUJI; ) is an Israeli public university, public research university based in Jerusalem. Co-founded by Albert Einstein and Chaim Weizmann in July 1918, the public university officially opened on 1 April 1925. ...

and produced by Kovax, to immunise fish against KHV. Israel is currently the only country in the world to vaccinate koi against the KHV. The vaccine is injected into the fish when they are under one year old, and is accentuated by using an

ultraviolet Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight and constitutes about 10% of ...

light. The vaccine has a 90% success rate and when immunized, the fish cannot succumb to a KHV outbreak and neither can the immunised koi pass KHV onto other fish in a pond. Only

biosecurity Biosecurity refers to measures aimed at preventing the introduction or spread of harmful organisms (e.g. viruses, bacteria, plants, animals etc.) intentionally or unintentionally outside their native range or within new environments. In agricult ...

measures such as prompt detection, isolation, and

disinfection A disinfectant is a chemical substance or compound used to inactivate or destroy microorganisms on inert surfaces. Disinfection does not necessarily kill all microorganisms, especially resistant bacterial spores; it is less effective than ...

of tanks and equipment can prevent the spread of the disease and limit the loss of fish stock. In 2002, spring viraemia struck an ornamental koi farm in

Kernersville, North Carolina Kernersville is a town in Forsyth County, North Carolina, Forsyth County, North Carolina, and the largest suburb of Winston-Salem. A small portion of the town is also in Guilford County, North Carolina, Guilford County. The population was 26,481 ...

, and required complete depopulation of the ponds and a lengthy quarantine period. For a while after this, some koi farmers in neighboring states stopped importing fish for fear of infecting their own stocks.

Breeding

When koi naturally breed on their own they tend to spawn in the spring and summer seasons. The male will start following the female, swimming right behind her and nudging her. After the female koi releases her eggs they sink to the bottom of the pond and stay there. A sticky outer shell around the egg helps keep it in place so it does not float around. Although the female can produce many spawns, many of the fry do not survive due to being eaten by others. 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 nonetheless exhibit a wide range of color and quality. Koi 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, are not 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 Arowanas are freshwater bony fish of the subfamily Osteoglossinae, also known as bony tongues (the latter name is now often reserved for Arapaiminae). In this family of fish, the head is bony and the elongated body is covered by large, heavy sca ...

due to the belief that it will enhance its color), while older culls, within their first year between 3 and 6 inches 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 Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean (also known as the Antarctic Ocean), it contains the geographic South Pole. ...

. They quickly revert to the natural coloration of an Amur carp within a few generations. In many areas, they are considered an

invasive species An invasive species is an introduced species that harms its new environment. Invasive species adversely affect habitats and bioregions, causing ecological, environmental, and/or economic damage. The term can also be used for native spec ...

and a pest. In the states of

Queensland Queensland ( , commonly abbreviated as Qld) is a States and territories of Australia, state in northeastern Australia, and is the second-largest and third-most populous state in Australia. It is bordered by the Northern Territory, South Austr ...

and

New South Wales New South Wales (commonly abbreviated as NSW) is a States and territories of Australia, state on the Eastern states of Australia, east coast of :Australia. It borders Queensland to the north, Victoria (state), Victoria to the south, and South ...

in Australia, they are considered noxious fish. In Japan, koi releases are sometimes held as an event for tourism purposes. However, as koi is artificial breed, this causes

genetic pollution Genetic pollution is a term for uncontrolled gene flow into wild populations. It is defined as "the dispersal of contaminated altered genes from genetically engineered organisms to natural organisms, esp. by cross-pollination", but has come to be ...

by breeding with native carps. Koi greatly increase the

turbidity Turbidity is the cloudiness or haziness of a fluid caused by large numbers of individual particles that are generally invisible to the naked eye, similar to smoke in air. The measurement of turbidity is a key test of both water clarity and wa ...

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. In many areas of North America, koi are introduced into the artificial "

water hazard A hazard is an area of a golf course in the sport of golf which provides a difficult obstacle, which may be of two types: (1) penalty areas such as lakes and rivers; and (2) bunkers. A penalty area was previously referred to as a water hazard ...

s" and ponds on golf courses to keep water-borne insect larvae under control through predation.

In common culture

In Japan, the koi is a symbol of

luck Luck is the phenomenon and belief that defines the experience of improbable events, especially improbably positive or negative ones. The Naturalism (philosophy), naturalistic interpretation is that positive and negative events may happen at a ...

prosperity Prosperity is the flourishing, thriving, good fortune and successful social status. Prosperity often produces profuse wealth including other factors which can be profusely wealthy in all degrees, such as happiness and health. Competing notions ...

, and

good fortune Good Fortune may refer to: * ''Good Fortune'' (film), a film by Aziz Ansari * "Good Fortune" (song), a song by PJ Harvey * ''Good Fortune'' (Brotherhood of Man album) * ''Good Fortune'' (78 Saab album) See also * Good fortune, the concept ...

, and also of

perseverance Perseverance most commonly refers to: * ''Perseverance'' (rover), a planetary rover landed on Mars by NASA * Psychological resilience Perseverance may also refer to: Geography * Perseverance, Queensland, a locality in Australia * Perseverance I ...

in the face of adversity. Ornamental koi are symbolic of

Japanese culture Japanese culture has changed greatly over the millennia, from the country's prehistoric Jōmon period, to its contemporary modern culture, which absorbs influences from Asia and other regions of the world. Since the Jomon period, ancestral ...

and are closely associated with the country's national identity. The custom of ''

koinobori , meaning in Japanese, are carp-shaped windsocks traditionally flown in Japan to celebrate , a traditional calendrical event which is now designated as , a national holiday in Japan. are made by drawing carp patterns on paper, cloth, or other ...

'' (carp streamers), which began in the

(1603–1867), is still practiced today and displayed in gardens on

Children's Day Children's Day is a commemorative date celebrated annually in honour of children, whose date of observance varies by country. In 1925, International Children's Day was first proclaimed in Geneva during the World Conference on Child Welfare. Sin ...

, 5 May. In Chinese culture, the koi represents fame, family harmony, and

wealth Wealth is the abundance of valuable financial assets or physical possessions which can be converted into a form that can be used for transactions. This includes the core meaning as held in the originating Old English word , which is from an ...

. It is a

feng shui Feng shui ( or ), sometimes called Chinese geomancy, is a traditional form of geomancy that originated in ancient China and claims to use energy forces to harmonize individuals with their surrounding environment. The term ''feng shui'' mean ...

favorite, symbolizing abundance as well as perseverance and strength, and has a mythical potential to transform into a

dragon A dragon is a Magic (supernatural), magical legendary creature that appears in the folklore of multiple cultures worldwide. Beliefs about dragons vary considerably through regions, but European dragon, dragons in Western cultures since the Hi ...

. Since the late 20th century, the keeping of koi in outdoor

s has become popular among the more affluent Chinese.

Koi pond Koi ponds are ponds used for holding koi carp, usually as part of a garden. Koi ponds can be designed specifically to promote health and growth of the Nishikigoi or Japanese Ornamental Carp. Koi ponds or lakes are a traditional feature of Ja ...

s are found in Chinese communities around the world, and the number of people who keep koi imported from Niigata, has been increasing. In addition, there are increasing numbers of Japanese koi bred in China that are sold domestically and exported to foreign countries.
The reason why wealthy Chinese started to buy a lot of Japanese "nishikigoi" 1/3
', Gendai Business. 29 March 2019.
The reason why wealthy Chinese started to buy a lot of Japanese "nishikigoi" 3/3
', Gendai Business. 29 March 2019. Koi are also popular in many countries in the equatorial region, where outdoor water gardens are popular. In

Sri Lanka Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka, also known historically as Ceylon, is an island country in South Asia. It lies in the Indian Ocean, southwest of the Bay of Bengal, separated from the Indian subcontinent, ...

, interior courtyards most often have one or several fish ponds dedicated to koi.

References

External links

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

Koi in the NIWA Atlas
{{Authority control Carp Fish of Japan Articles containing video clips National symbols of Japan