Editing Koi

{{Short description|Colored varieties of Amur carp}}
{{Other uses}}
{{Use dmy dates|date=December 2014}}
{{Infraspeciesbox
| name =Koi fish 
| image = Ojiya Nishikigoi no Sato ac (3).jpg
| image_alt = 
| image_caption = 
| status = DOM
| genus = Cyprinus
| species = rubrofuscus
| varietas = koi or nishikigoi
| authority = [[Bernard Germain de Lacépède|Lacépède]], 1803
| synonyms = * ''Cyprinus carpio'' Linnaeus, 1758
* ''Cyprinus carpio ssp. rubrofuscus'' Lacepède, 1803
* ''Cyprinus carpio haematopterus'' Temminck & Schlegel, 1846
| synonyms_ref = 
}}
[[File:Koiinapond-swimming-fall-2011.ogv|thumb|Several koi swim around in a pond in Japan. (video)]]
[[File:Koi Carp. (16999185026).jpg|thumb|A school of koi containing multiple different varieties]]
{{Nihongo|'''Koi'''|[[:ja:鯉|鯉]] ||{{IPA|ja|koꜜi|lang}}, literally "carp"}}, or more specifically {{Nihongo|'''''nishikigoi'''''|[[:ja:錦鯉|錦鯉]] |extra={{IPA|ja|ɲiɕi̥kiꜜɡoi|lang}}, literally "[[brocade]]d carp"}}, are colored varieties of carp (''[[Cyprinus]]'' sp.) that are kept for decorative purposes in outdoor [[koi pond]]s or [[water garden]]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]] in the early 19th century.<ref name = "jokc">[https://www.researchgate.net/publication/285770347_Japanese_Ornamental_Koi_Carp_Origin_Variation_and_Genetics Japanese Ornamental Koi Carp: Origin, Variation and Genetics] {{Webarchive|url=https://web.archive.org/web/20201220170350/https://www.researchgate.net/publication/285770347_Japanese_Ornamental_Koi_Carp_Origin_Variation_and_Genetics |date=20 December 2020 }} May 2015</ref><ref name = "ojiyamuse">[https://web.archive.org/web/20200130222024/https://www.nishikigoinosato.jp/eng/index.html Ojiya Nishikigoi no Sato Museum]</ref><ref name = "znahisja"/> 

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 [[Kohaku (Nishikigoi)|''Kōhaku'']], ''Taishō Sanshoku'' and [[Showa (fish)|''Shōwa Sanshoku'']] varieties.

== History ==
[[Carp]] are a large group of fish species originally native to [[Central Europe]] and [[Asia]]. [[Asian carp|Various carp species]] were originally [[Domestication|domesticated]] in [[China]], where they were used primarily for consumption. 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.

=== Prehistory ===
In Japan, [[Miocene]] fossils of the [[Cyprinidae|carp family]] (''Cyprinidae'') have been excavated from [[Iki Island]], [[Nagasaki Prefecture]].<ref name = "Yabumoto">{{Cite journal |last = Yabumoto |first = Yoshitaka |title = Ikiculter chojabaruensis, a New Genus and Species of Cyprinid Fish from the Miocene of Iki Island, Nagasaki, Japan |journal = Paleontological Research |volume = 14 |issue = 4 |date = 2010 |pages = 277–292 |doi = 10.2517/1342-8144-14.4.277 |s2cid = 85972532 }}</ref> Furthermore, numerous carp [[pharyngeal teeth]] have been excavated from [[Jomon]] and [[Yayoi period|Yayoi]] period sites.<ref name = "Nakajima2011">{{Cite journal |last = Nakajima |first = Tsuneo |title = コイ科魚類咽頭歯遺存体から見える先史時代の漁撈と稲作との関係に関する一考察 |trans-title = A Speculation on Relationships between Freshwater Fishing and Rice Cultivation in Prehistoric Ages from a Viewpoint of Tooth Remains of Carps |journal = Bulletin of the National Museum of Japanese History |volume = 162 |publisher = National Museum of Japanese History |date = 31 January 2011 |doi = 10.15024/00001857 |pages = 49–63 }}</ref> For example, pharyngeal teeth of the extinct species ''Jōmon Koi'' (''Cyprinus sp.'')  in addition to the modern species of carp (''[[Cyprinus carpio]]'' or ''[[Cyprinus rubrofuscus]]'') have been excavated from the Akanoi Bay lakebed site ({{lang|ja|赤野井湾湖底遺跡}}) in [[Lake Biwa]] at the end of the Early Jomon Period (11,500 – 7,000 years ago).<ref name = "Nakajima2011" /> 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 ({{lang|ja|粟津湖底遺跡}}) dating from the Middle Jomon Period (5500 – 4400 years ago).<ref name = "Nakajima2011" />

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.<ref name = "Nakajima2011" /><ref name = "Nakajima2010">{{Cite journal |last1 = Nakajima |first1 = T. |last2 = Nakajima |first2 = M. |last3 = Yamazaki |first3 = T. |title = Evidence for fish cultivation during the Yayoi Period in western Japan |journal = International Journal of Osteoarchaeology |volume = 20 |issue = 2 |date = 2010 |pages = 127–134 |doi = 10.1002/oa.1005 }}</ref>

It was previously thought that all Japanese carp were introduced from China in prehistoric times.<ref>{{Cite journal |last1 = Jordan |first1 = David Starr |last2 = Fowler |first2 = Henry W |title = A review of the cyprinoid fishes of Japan. |journal = Proc. U.S. Natl. Mus. |issue = 1334 |date = 1903 |volume = 26 |pages = 811–862 |doi = 10.5479/si.00963801.26-1334.811 |url = https://www.biodiversitylibrary.org/part/9451 |access-date = 4 January 2024 |archive-date = 14 March 2023 |archive-url = https://web.archive.org/web/20230314064516/https://www.biodiversitylibrary.org/part/9451 |url-status = live }}</ref> However, recent analysis of [[mitochondrial DNA]]  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.<ref name="onlinelibrary.wiley.com">{{Cite journal|last1=Mabuchi|first1=K.|last2=Senou|first2=H.|last3=Suzuki|first3=T.|last4=Nishida|first4=M.|date=June 2005|title=Discovery of an ancient lineage of Cyprinus carpio from Lake Biwa, central Japan, based on mtDNA sequence data, with reference to possible multiple origins of koi|url=https://onlinelibrary.wiley.com/doi/10.1111/j.0022-1112.2005.00676.x|journal=Journal of Fish Biology|volume=66|issue=6|pages=1516–1528|language=en|doi=10.1111/j.0022-1112.2005.00676.x|bibcode=2005JFBio..66.1516M|issn=0022-1112|url-access=subscription|access-date=3 October 2023|archive-date=10 October 2023|archive-url=https://web.archive.org/web/20231010105228/https://onlinelibrary.wiley.com/doi/10.1111/j.0022-1112.2005.00676.x|url-status=live}}</ref> Moreover, the oldest record of the introduction of non-native fish in Japan is that of goldfish from China (1502 or 1602),<ref>{{Cite book |editor = Kokusho Kanko-kai |title = 雑芸叢書 |trans-title = Miscellaneous Art Series |volume = 1 |publisher = Kokusho Kan-kai |date = 1915 |doi = 10.11501/1869566 |page = 265 |author1 = 国書刊行会 }}</ref> and there is no record of carp (including colored carp) until the introduction of the [[mirror carp]], called ''Doitsugoi'' (German carp), in 1904.<ref>{{Cite book |last = Maruyama |first = Tamezo |title = 外国産新魚種の導入経過 |trans-title = Progress of introduction of new foreign fish species |publisher = Fisheries Agency, Research Department, Resources Division |date = March 1987 }}</ref>

=== Middle Ages ===
In the Japanese history book ''[[Nihon Shoki]]'' (Chronicles of Japan, 720), it is written that [[Emperor Keikō]] released carp in a pond for viewing when he visited [[Mino Province]] (present [[Gifu Prefecture]]) in the fourth year of his reign (74 AD). In Cui Bao's ''Gǔjīnzhù'' ({{lang|zh|古今注}}, Annotations on the Ancient and Modern Period) from the [[Western Jin Dynasty]] (4th century A.D.) in China, carp of the following colors are described: red horse ({{lang|zh|赤驥}}), blue horse ({{lang|zh|青馬}}), black horse ({{lang|zh|玄駒}}), white horse ({{lang|zh|白騏}}), and yellow pheasant ({{lang|zh|黄雉}}).<ref>{{Cite web|url=https://zh.wikisource.org/wiki/%E5%8F%A4%E4%BB%8A%E6%B3%A8|title=古今注 - 维基文库，自由的图书馆|website=zh.wikisource.org|access-date=3 October 2023|archive-date=2 October 2023|archive-url=https://web.archive.org/web/20231002023338/https://zh.wikisource.org/wiki/%E5%8F%A4%E4%BB%8A%E6%B3%A8|url-status=live}}</ref> 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 ''[[:ja:本草和名|Honzō Wamyō]]'' ({{lang|ja|本草和名}}, 918) mentions red carp ({{lang|ja|赤鯉}}), blue carp ({{lang|ja|青鯉}}), black carp ({{lang|ja|黒鯉}}), white carp ({{lang|ja|白鯉}}), and yellow carp ({{lang|ja|黄鯉}}) as Japanese names corresponding to the above Chinese names, suggesting that carp of these colors existed in China and Japan in those days.<ref>{{Cite book |editor-last = Fukae |editor-first = Sukehito |title = 本草和名 |trans-title = Honzō Wamyō |volume = 2 |publisher = Japan Society for the Publication of Complete Works of Classical Japanese Literature |date = 1927 |page = 19 |doi = 10.11501/1111774  |author1 = 深江, 輔仁, 平安中期 |author2 = 与謝野, 寛, 1873-1935 }}</ref> In addition, Hitomi Hitsudai's drug dictionary ''Honchō Shokkan'' ({{lang|ja|本朝食鑑}}, Japanese Medicine Encyclopedia, 1697) states that red, yellow, and white carp of the three colors were in Japan at that time.<ref>{{Cite book |last = Hitomi |first = Hitsudai |title =本朝食鑑 |trans-title = Japanese Medicine Encyclopedia |volume = 7 |publisher = Hirano Uji Denzaemon, Hiranoya Katsuzaemon |date = 1697 |doi = 10.11501/2569419 }}</ref>

However, it is believed that these single-colored carp were not a variety created by [[Selective breeding|artificial selection]], as is the case with today's koi, but rather a mutation-induced color change.<ref>{{Cite journal |last = Nakajima |first = Kenji |title = 魚病学基礎講座(錦鯉篇)1 |trans-title = Basic Fish Pathology (Nishikigoi) 1 |journal = Journal of the Japan Veterinary Medical Association |volume = 29 |issue = 1 |publisher = Japan Veterinary Medical Association |date = January 1976 |pages = 20–24 |doi = 10.12935/jvma1951.29.20 |issn = 0446-6454 |url = https://agriknowledge.affrc.go.jp/RN/2010123255 |access-date = 3 October 2023 |archive-date = 27 September 2023 |archive-url = https://web.archive.org/web/20230927112708/https://agriknowledge.affrc.go.jp/RN/2010123255 |url-status = live }}</ref> 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%.<ref>{{Cite book |editor-last = Kawamoto |editor-first = Nobuyuki |title = 養魚学各論 |trans-title = Introduction to Fish Farming |publisher = Koseisha Koseikaku |date = 1967 |doi = 10.11501/2513721 |page = 59 |author1 = 川本, 信之, 1898-1985 }}</ref>

The Amur carp (''[[Cyprinus rubrofuscus]]'') is a member of the cyprinid family [[species complex]] native to [[East Asia]]. 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''.<ref name="IUCN carpio">{{cite iucn |author=Freyhof, J. |author2=Kottelat, M. |date=2008 |title=''Cyprinus carpio'' |volume=2008 |page=e.T6181A12559362 |doi=10.2305/IUCN.UK.2008.RLTS.T6181A12559362.en |access-date=11 November 2021}}</ref> Amur carp have been [[aquaculture]]d as a food fish at least as long ago as the fifth century BC in China.

=== Modern period ===
[[File:Rice terraces, Yamakoshi, Niigata.jpg|thumb|alt=Terraced rice paddies in Yamakoshi, Niigata Prefecture|Terraced rice paddies in Yamakoshi, Niigata Prefecture]]
The systematic breeding of ornamental Amur carp began in the 1820s in an area known as "Nijūmuragō" ({{lang|ja|二十村郷}}, {{lit|twenty villages|lk=yes}}) which spans [[Ojiya, Niigata|Ojiya]] and [[Yamakoshi, Niigata|Yamakoshi]] in [[Niigata Prefecture]] (located on the northeastern coast of [[Honshu]]) in Japan. In Niigata Prefecture, Amur carp were farmed for food in Musubu Shinden, Kanbara County (present Akiba Ward, [[Niigata (city)|Niigata City]]) from the end of the [[Genna]] era (1615–1624).<ref>{{Cite book |last = Fujita |first = Masakatsu |title = 養魚経営学 |trans-title = Fish Farming Management |publisher = Suisan Shoin |date = November 1906 |doi = 10.11501/802628 |page = 18 }}</ref> 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 [[:ja:東山村 (新潟県古志郡)|Higashiyama Village]] and Juni Shrine in [[:ja:東竹沢村|Higashitakezawa Village]].<ref name = "tohaku">{{Cite book |editor = Tokyo Prefecture |title = 東京大正博覧会審査報告 |trans-title = Tokyo Taisho Exposition Examination Report |volume = 2 |publisher = Tokyo Prefecture |date = 1916 |page = 861 |doi = 10.11501/954707 |author1 = 東京府 }}</ref>

During the [[Bunka]] and [[Bunsei]] 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.<ref name = "tohaku" />

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.<ref>{{Cite book |editor = Niigata Prefectural Fisheries Experiment Station |title = 農家の副業的養魚法 |trans-title = Farmers' Sideline Fish Farming Methods |volume = 1 |publisher = Niigata Agricultural Society |date = 1931 |doi = 10.11501/1226542 |page = 100 |author1 = 新潟県水産試験場 }}</ref> 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.<ref name = "jokc"/><ref name = "znahisja"/>

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'' ({{lang|ja|隠田}}), 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'' ({{lang|ja|斑鯉}}, {{lit|spotted carp|lk=yes}}), ''Kawarigoi'' ({{lang|ja|変鯉}}, {{lit|variant carp|lk=yes}}), ''Irogoi'' ({{lang|ja|色鯉}}, {{lit|colored carp|lk=yes}}), ''Moyōgoi'' ({{lang|ja|模様鯉}}, {{lit|patterned carp|lk=yes}}), and so on.

A geographical book on [[Suruga Province]] (present-day [[Shizuoka Prefecture]]), 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)."<ref>{{Cite book |last = Abe |first = Masanobu |title = 駿国雑志 2 |trans-title = Suruga Miscellaneous Records 2 |publisher = Yoshimi Shoten |date = February 1977 |page = 311 |doi = 10.11501/9537491 }}</ref> This probably refers to two- or three-colored carp caused by mutation, and is a valuable record of ''Nishikigoi'' of the [[Edo period]] (1603 – 1868).

[[File:Sanshoku goi.jpg|thumb|Illustration of a three-colored carp in Ritsurin Garden, 1900. This is the oldest illustration of koi. It has the kanji characters for ''asagi'' on its back and red on its belly.]]
In 1900, there was a three-colored carp in [[Ritsurin Garden]] in [[Takamatsu]], [[Kagawa Prefecture]], and the price was over 1,000 yen per fish, which was a high price for that time.<ref>{{Cite book |last = Miyoshi |first = Otojiro |title = 金魚問答 |trans-title = Goldfish Question and Answer |publisher = Mataoma Yasujiro |date = 1903 |page = 79 |doi = 10.11501/904129 }}</ref> 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.

[[File:Odd-eyed cat and Koi.jpg|thumb|Odd-eyed cat and Spotted carp, from the magazine ''Shonen'', 1910.]]
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.<ref>{{Cite magazine |last = Toyama |first = Kametaro |title = 金銀目の猫と源平咲別の花 |trans-title = Cat with gold and silver eyes and blooming flowers of two mixed colors |magazine = Shōnen |issue = 82 |publisher = Jijishinposha |date = June 1910 |doi = 10.11501/1793889 | page =143 }}</ref> The price of ''Nishikigoi'' at a fish show in [[Fukagawa, Tokyo|Fukagawa]], 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 [[:ja:東京大正博覧会|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.<ref>{{Cite book |editor = Tokyo Taisho Exposition |title = 東京大正博覧会出品審査概況 : 附・受賞人名簿  |trans-title = Overview of the Judging of Exhibits at the Tokyo Taisho Exposition |publisher = Tokyo Taisho Exposition Memorial Book Publishing Society |date = 1914 |page = 63 |doi = 10.11501/951452 |author1 = 東京大正博覧会 }}</ref> After the exposition closed, they presented eight koi to the Crown Prince ([[Emperor Showa]]). 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 [[Taishō era|Taisho era]] (1912–1926), after he admired the ''Taishō Sanshoku'' when he first saw it.<ref>{{Cite book |last = Tanaka |first = Shigeho |title = 日本の魚類 |trans-title = Fish of Japan |publisher = Dai Nippon Tosho |date = 1936 |page = 319 }}</ref><ref>{{Cite magazine |url = https://www.maff.go.jp/j/pr/aff/2308/spe1_03.html |title = 年々、人気上昇中！ 錦鯉の魅力 |trans-title = Increasingly popular every year! Attraction of Nishikigoi |magazine = aff |publisher = Ministry of Agriculture, Forestry and Fisheries |date = August 2023 |access-date = 7 October 2023 |archive-date = 7 October 2023 |archive-url = https://web.archive.org/web/20231007025804/https://www.maff.go.jp/j/pr/aff/2308/spe1_03.html |url-status = live }}</ref> In 1917, the fixation of ''Kōhaku'' (by Kunizo Hiroi), which had first been produced in the 1880s, was also assured.<ref name = "Tokuma">{{Cite book |editor = Tokuma Shoten |title = 錦鯉の魅力 : 泳ぐ宝石を育てるために |trans-title = Attraction of Nishikigoi : To raise swimming jewels |publisher = Tokuma Shoten |date = 1966 |doi = 10.11501/2510714 |author1 = 徳間書店 }}</ref>

Apart from the koi of Niigata Prefecture's Nijūmuragō area, there is a variety called ''Shūsui'' ({{lang|ja|秋翠}}), which was created by Tokyo-based goldfish breeder Kichigoro Akiyama in 1906 by crossing a female [[leather carp]] imported from Germany with a male Japanese ''Asagi'' or spotted carp.<ref name = "Tokuma" /> 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]] held in San Francisco.<ref>{{Cite book |editor = Supervisory Bureau of the Ministry of Commerce and Industry |title = 紐育金門万国博覧会政府参同事務報告書 |trans-title = Report of the Government Visit to the [[Golden Gate International Exposition]] |publisher = Supervisory Bureau of the Ministry of Commerce and Industry |date = 1941 |page = 122 |doi = 
10.11501/1716726 |author1 = 商工省監理局 }}</ref>

=== 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.<ref>{{Cite web |url=http://www.mpks.org/articles/RayJordan/KoiHistory3.shtml |title=MPKS Ray Jordan Koi History |publisher=Ray Jordan |access-date=26 April 2009 |url-status=dead |archive-url=https://web.archive.org/web/20090723111340/http://www.mpks.org/articles/RayJordan/KoiHistory3.shtml |archive-date=23 July 2009 }}</ref><ref>{{Cite web |url=http://www.netpets.org/fish/reference/freshref/nishi.html |title=Early Records |publisher=Netpets.org |access-date=11 April 2009 |archive-date=13 June 2010 |archive-url=https://web.archive.org/web/20100613053139/http://netpets.org/fish/reference/freshref/nishi.html |url-status=live }}</ref> Collecting koi has become a social hobby. Passionate hobbyists join clubs, share their knowledge and help each other with their koi.<ref>{{Cite book |url=https://books.google.com/books?id=JfgI8wUC5JQC&q=koi+fish+information |title=The Ultimate Koi |last=Fletcher |first=Nick |date=1 January 1999 |publisher=Interpet |isbn=978-1-86054-146-9 |language=en |access-date=18 October 2020 |archive-date=16 May 2024 |archive-url=https://web.archive.org/web/20240516033009/https://books.google.com/books?id=JfgI8wUC5JQC&q=koi+fish+information#v=snippet&q=koi%20fish%20information&f=false |url-status=live }}</ref> 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.<ref name = "gendai1"/><ref name = "gendai3"/>

== Etymology ==
[[File:Koi pond Hilo Hawaiin Hotel.jpg|thumb|Koi in an artificial pond at a hotel in [[Hilo]]]]
The words "koi" and "nishikigoi" come from the Japanese words 鯉 (carp), and 錦鯉 (brocaded carp), respectively. In Japanese, "koi" is a [[homophone]] 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]], 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.<ref name = "znahisja">[https://web.archive.org/web/20200208143056/http://zna.jp/nishikigoi/index.html The History of Nishikigoi 錦鯉とその起源] Zen Nippon Airinkai</ref>

== Taxonomy ==
[[File:Cyprinus haematopterus.jpg|thumb|alt=Cyprinus haematopterus|''Cyprinus haematopterus'']]
[[File:Cyprinus melanotus and Cyprinus conirostris.jpg|thumb|alt=Cyprinus melanotus and Cyprinus conirostris|''Cyprinus melanotus'' and ''Cyprinus conirostris'']]
The koi are a group of breeds produced by artificial selection primarily from black carp called ''[[:ja:ノゴイ|nogoi]]'' ({{lang|ja|野鯉}}, {{lit|wild carp|lk=yes}}) or ''magoi'' ({{lang|ja|真鯉}}, {{lit|true carp|lk=yes}}), which inhabit lakes, ponds, and rivers in Japan. The black carp refers to the [[Eurasian carp]] (''Cyprinus carpio''), which was previously thought to have been introduced to Japan from Eurasia in prehistoric times.

[[Philipp Franz von Siebold]] of the Netherlands, who stayed in Japan during the Edo period, reported in ''[[Fauna Japonica]]'' (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.<ref name="onlinelibrary.wiley.com"/> Currently, the Japanese native carp is assumed to be ''Cyprinus melanotus'', and a new scientific name for it is being considered.<ref>{{Cite web |last = Seno |first = Hiroshi |title = 日本産コイ(コイ目コイ科)のルーツ解明と保全へのシナリオ |trans-title = Elucidation of the Roots of Japanese Carp and Scenarios for Conservation |date = 2010 |publisher = KAKEN |url = https://kaken.nii.ac.jp/report/KAKENHI-PROJECT-18510209/185102092008jisseki/ |access-date = 8 October 2023 |archive-date = 16 May 2024 |archive-url = https://web.archive.org/web/20240516033050/https://kaken.nii.ac.jp/report/KAKENHI-PROJECT-18510209/185102092008jisseki/ |url-status = live }}</ref>

''Cyprinus haematopterus'' is thought to refer to the [[Amur carp]] of Eurasian origin, traditionally called ''Yamatogoi'' ({{lang|ja|大和鯉}}, {{lit|carp of Yamato Province|lk=y}}) in Japan. ''Yamatogoi'' have been famous since the Edo period as farmed carp in [[Yamato Province]] (now [[Nara Prefecture]]). Other carp of the same type as ''Yamatogoi'' are known as ''Yodogoi'' ({{lang|ja|淀鯉}}, [[Yodo River]] carp) from [[Osaka Prefecture|Osaka]] and ''Shinshūgoi'' ({{lang|ja|信州鯉}}, introduced ''Yodogoi'') from [[Nagano 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.<ref>{{Cite journal |last = Higuchi |first = Masahito |title = ミトコンドリア DNA 調節領域の塩基配列からみたニシキゴイの遺伝的変異とその起源 |trans-title = Genetic variability and ancient origin of the Japanese ornamental carp (koi) using the nucleotide sequences of mitochondrial DNA control region |journal = Aquatic Animals |volume = 2023.0_AA2023-18 |publisher = Aquos Institute |date = 23 August 2023 |doi = 10.34394/aquaticanimals.2023.0_AA2023-18 }}</ref>

In the past, koi were commonly believed to have been bred from the [[common carp]] (''Cyprinus carpio''). Extensive [[Hybrid (biology)|hybridization]] between different populations, coupled with widespread translocations, has muddled the historical [[zoogeography]] of the common carp and [[Cyprinus|its relatives]]. Traditionally, [[Cyprinus rubrofuscus|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,<ref name="IUCN carpio"/> leading recent authorities to recognize them as a separate species, ''C. rubrofuscus'' (''C. c. haematopterus'' being a [[junior synonym]]).<ref>{{cite iucn |author=Huckstorf, V. |date=2012 |title=''Cyprinus rubrofuscus'' |volume=2012 |page=e.T166052A1108337 |doi=10.2305/IUCN.UK.2012-1.RLTS.T166052A1108337.en |access-date=11 November 2021}}</ref><ref>{{FishBase | genus = Cyprinus | species = rubrofuscus | id=59920 | month = November | year = 2016}}</ref> 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),<ref>{{cite journal |title=Discovery of an ancient lineage of ''Cyprinus carpio'' from Lake Biwa, central Japan, based on mtDNA sequence data, with reference to possible multiple origins of koi |journal=Journal of Fish Biology |volume=66 |issue=6 |pages=1516 |doi=10.1111/j.0022-1112.2005.00676.x |year=2005 |last1=Mabuchi |first1=K. |last2=Senou |first2=H. |last3=Suzuki |first3=T. |last4=Nishida |first4=M.|bibcode=2005JFBio..66.1516M }}</ref> 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.<ref name="Grossa">{{Cite journal |last=Grossa |first=Riho |author2=Klaus Kohlmannb |author3=Petra Kerstenb |name-list-style=amp |date=2002 |title=PCR–RFLP analysis of the mitochondrial ND-3/4 and ND-5/6 gene polymorphisms in the European and East Asian subspecies of common carp (''Cyprinus carpio'' L.) |journal=Aquaculture |volume=204 |issue=3–4 |pages=507–516 |doi=10.1016/S0044-8486(01)00836-5|bibcode=2002Aquac.204..507G }}</ref><ref name="Chistiakov">{{cite journal |title=Genetic evolution and diversity of common carp ''Cyprinus carpio'' L. |journal=Central European Journal of Biology |volume=4 |issue=3 |pages=304–312 |doi=10.2478/s11535-009-0024-2 |year=2009 |last1=Chistiakov |first1=D.A. |last2=Voronova |first2=N.V|doi-access=free }}</ref><ref name="Xu2014">{{cite journal |title=Genome sequence and genetic diversity of the common carp, ''Cyprinus carpio'' |journal=Nature Genetics |volume=46 |issue=11 |pages=1212–1219 |doi=10.1038/ng.3098 |pmid=25240282 |year=2014 |last1=Xu |first1=P. |display-authors=etal|doi-access=free }}</ref> 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''.<ref name="IUCN carpio" /><ref>{{cite book |title=Freshwater Fisheries Ecology |publisher=Wiley-Blackwell |page=297 |isbn=978-1-118-39442-7 |year=2015 |last1=Craig |first1=J.F.}}</ref> Regardless, a [[Taxonomy (biology)|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,<ref name="Chistiakov" /> with one study of mtDNA suggesting that koi are close to the Southeast Asian carp, but not necessarily the Chinese.<ref>{{cite journal |title=Using mitochondrial nucleotide sequences to investigate diversity and genealogical relationships within common carp (''Cyprinus carpio'' L.) |journal=Anim. Genet. |volume=1 |issue=1 |pages=22–28 |doi=10.1111/j.1365-2052.2004.01215.x |pmid=15670127 |year=2005 |last1=Thai |first1=B.T. |last2=Burridge |first2=C.P. |last3=Pham |first3=T.A. |last4=Austin |first4=C.M.}}</ref>

== Varieties ==
[[File:Ojiya Nishikigoi no Sato ac (4).jpg|thumb|The [[Ojiya, Niigata|Ojiya]] no Sato Museum in [[Niigata Prefecture]], Japan, is the only museum in the world that exhibits both varieties of living koi and data that show the history of their breeding.<ref name = "ojiyamuse"/>]]

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.<ref name = "znavar">[https://web.archive.org/web/20200218055159/http://zna.jp/eng/nishikigoi/variety/index.html The Varieties of Nishikigoi] Zen Nippon Airinkai</ref> 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 {{Nihongo|''Gosanke''|御三家}}, which is made up of the ''Kōhaku'', ''Taishō Sanshoku'', and ''Shōwa Sanshoku'' varieties.

New koi varieties are still being actively developed.<ref>{{cite web |url=http://www.mitchkoi.co.uk/koikeepingtips/koi-varieties/ |title=Guide to Koi Varieties |work=mitchkoi.co.uk |access-date=12 April 2014 |archive-date=12 April 2014 |archive-url=https://archive.today/20140412171302/http://www.mitchkoi.co.uk/koikeepingtips/koi-varieties/ |url-status=dead }}</ref> Ghost koi developed in the 1980s have become very popular in the [[United Kingdom]]; they are a [[Hybrid (biology)|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<ref>{{Cite web |last=Scientist |first=Atsushi Hoshino |date=22 December 2023 |title=Research campaign on butterfly koi fish |url=https://zenkoifarm.vn/ca-koi-buom-gia-bao-nhieu-dac-diem-va-cach-cham-soc-nhu-the-nao/ |access-date=8 February 2024 |website=Zen Koi Garden Biological Research Center |language=vi |archive-date=7 February 2024 |archive-url=https://web.archive.org/web/20240207175948/https://zenkoifarm.vn/ca-koi-buom-gia-bao-nhieu-dac-diem-va-cach-cham-soc-nhu-the-nao/ |url-status=live }}</ref> and ghost koi are considered by some to be not true ''nishikigoi''.<ref>{{Cite web |last=Informer (Abi) |first=Pond |date=13 February 2022 |title=Complete Guide to Ghost Koi |url=https://pondinformer.com/ghost-koi-guide/ |access-date=7 September 2022 |website=Pond Informer |language=en |archive-date=7 September 2022 |archive-url=https://web.archive.org/web/20220907123546/https://pondinformer.com/ghost-koi-guide/ |url-status=live }}</ref>

The major named varieties include:<ref name = "znavar"/>
<!-- {{columns-list|6|
# ''Kohaku
# ''Taisho Sanke
# ''Showa Sanke
# ''Tanchō
# ''Chagoi
# ''Asagi
# ''Utsurimono
# ''Bekko
# ''Goshiki
# ''Shūsui
# ''Kinginrin
# ''Kawarimono
# ''Ōgon
# ''Kumonryū
# ''Ochiba
# ''Koromo
# ''Hikari-moyomono
# ''Kikokuryū
# ''Kin-Kikokuryū
# Ghost koi
# Butterfly koi
# ''Doitsu-goi
}}
 -->
* {{Nihongo|''[[Kohaku (Nishikigoi)|Kōhaku]]''|紅白}} 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).<ref>{{Cite book |author=Tamadachi M apter=Koi varieties |page=191 |title=The Cult of the Koi |publisher=TFH Publications |location=Neptune City, New Jersey |year=1990 |isbn=978-0-86622-085-9}}</ref>
* {{Nihongo|''Taishō Sanshoku'' (or ''Taishō Sanke)''|大正三色}} is very similar to the ''kōhaku'', except for the addition of small black markings called {{Nihongo|''sumi''|墨}}. This variety was first exhibited in 1914 by the koi breeder Gonzo Hiroi, during the reign of the [[Taishō Emperor]].{{Citation needed|date=April 2009}} 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).
* {{Nihongo|[[Showa (fish)|''Shōwa Sanshoku'' (or ''Shōwa Sanke'')]]|昭和三色}} 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.''
* {{Nihongo|''Bekkō''|鼈甲、べっ甲}} is a white-, red-, or yellow-skinned koi with black markings {{Nihongo|''sumi''|墨}}. The Japanese name means "tortoise shell", and is commonly written as 鼈甲. The white, red, and yellow varieties are called {{Nihongo|''Shiro Bekkō''|白鼈甲}}, {{Nihongo|''Aka Bekkō''|赤鼈甲}} and {{Nihongo|''Ki Bekkō''|黄鼈甲}}, respectively. It may be confused with the ''Utsuri''.
* {{Nihongo|''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 {{Nihongo|"black and yellow markings"|黒黄斑|''Kuro ki madara''}} in the 19th century, but renamed {{Nihongo|''Ki Utsuri''|黄写り}} by Elizaburo Hoshino, an early 20th-century koi breeder. The red and white versions are called {{Nihongo|''Hi Utsuri''|緋写り}} and {{Nihongo|''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 ''Shōwa'', but lacking either red pigment (''Shiro Utsuri'') or white pigment (''Hi Utsuri''/''Ki Utsuri'').
* {{Nihongo|''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]].
* '{{Nihongo|''Shūsui''|秋翠}} means "autumn green"; the ''Shūsui'' was created in 1910 by Yoshigoro Akiyama（[[:ja:秋山　吉五郎|秋山　吉五郎]], by crossing Japanese ''Asagi'' with German [[mirror carp]].{{Citation needed|date=April 2009}} 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.
* {{Nihongo|''Koromo''|衣}} 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''.{{Citation needed|date=April 2009}} The most commonly encountered ''Koromo'' is an {{Nihongo|''Ai Goromo''|藍衣}}, 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 {{Nihongo|''Budō-Goromo''|葡萄衣}}, which has a darker (burgundy) ''hi'' overlay that gives it the appearance of bunches of grapes. Very rarely seen is the {{Nihongo|''Sumi-Goromo''|墨衣}}, which is similar to ''Budō-Goromo'', but the ''hi'' pattern is such a dark burgundy that it appears nearly black.
* {{Nihongo|''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 {{Nihongo|''kawarigoi''|変わり鯉}}.{{Citation needed|date=April 2009}}
* {{Nihongo|''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.
* {{Nihongo|''Hikari-mujiimono''|光無地もの}} 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.
* {{Nihongo|''Hikari-moyomono''|光模樣もの}} is a koi with colored markings over a metallic base or in two metallic colors.
* {{Nihongo|''Hikari-utsurimono''|光写りもの}} is a cross between ''utsurimono'' series and ''Ōgon''.
* {{Nihongo|''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.
* {{Nihongo|''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.
* {{Nihongo|''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.
* {{Nihongo|''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.<!-- 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.-->
* {{Nihongo|''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.<ref name="theblogadventure.com">{{Cite web |date=11 August 2023 |title=19 Features of Koi Fish: from Symbolism to Serenity |url=https://theblogadventure.com/koi-fish-19aspects-from-symbolism-to-serenity/ |access-date=15 August 2023 |language=en-US |archive-date=15 August 2023 |archive-url=https://web.archive.org/web/20230815191833/https://theblogadventure.com/koi-fish-19aspects-from-symbolism-to-serenity/ |url-status=live }}</ref> ''Kumonryu ''compete in the ''Kawarimono'' category.
* {{Nihongo|''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".
* ''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 ([[:ja:人面魚|人面魚]]、[[:ja:じんめんぎょ|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]] ([[:ja:鰭長錦鯉|鰭長錦鯉]]、[[:ja:ひれながにしきごい|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''.
* {{Nihongo|''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).

<gallery>
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
</gallery>

== Differences from goldfish ==
[[File:Koi head closeup.jpg|thumb|right|Koi have prominent [[barbels]] on the lip that are not visible in goldfish.]]

[[Goldfish]] (''Carassius auratus'') were developed in [[China]] more than a thousand years ago by [[selectively breeding]] colored varieties; by the [[Song dynasty]] (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.<ref name="bristol">{{Cite web |url=http://www.bristol-aquarists.org.uk/goldfish/info/info.htm |title=Background information about goldfish |access-date=28 July 2006 |archive-date=15 December 2011 |archive-url=https://web.archive.org/web/20111215015531/http://www.bristol-aquarists.org.uk/goldfish/info/info.htm |url-status=live }}</ref> 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]], [[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.<ref>{{cite web |title=Koi Fish vs Goldfish: 10 Differences to Help You Distinguish Them |url=https://www.fishtankworld.com/koi-fish-vs-goldfish/ |website=Fish Tank World |access-date=3 September 2021 |date=5 April 2019 |archive-date=3 September 2021 |archive-url=https://web.archive.org/web/20210903043939/https://www.fishtankworld.com/koi-fish-vs-goldfish/ |url-status=live }}</ref> Goldfish and koi can interbreed; however, as they were developed from different species of carp, their offspring are sterile.<ref>{{cite web |title=The difference between koi and goldfish |url=http://www.livingthecountrylife.com/animals/difference-between-koi-and-goldfish/page/0/1 |website=Living the Country Life |url-status=dead |archive-url=https://web.archive.org/web/20191118145003/http://www.livingthecountrylife.com/animals/difference-between-koi-and-goldfish|archive-date=18 November 2019}}</ref><ref name="Aquatic-oasis">{{Cite web |url=http://www.aquatic-oasis.com/articles.htm |title=Aquatic-oasis articles |publisher=Aquatic-oasis |access-date=2 February 2012 |url-status=dead |archive-url=https://web.archive.org/web/20100622235948/http://www.aquatic-oasis.com/articles.htm |archive-date=22 June 2010}}</ref>

== Health, maintenance, and longevity ==
[[File:Yuyuan Garden.jpg|thumb|left|upright|Koi in [[Yu Garden]], [[Shanghai]]]]
The Amur carp is a hardy fish, and koi retain that durability. Koi are coldwater fish, but benefit from being kept in the {{convert|15|–|25|C|F}} range, and do not react well to long, cold, winter temperatures; their immune systems are very weak below {{convert|10|C|F}}. 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 {{convert|1.5|m|ft|frac=2|abbr=on}}. 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]]s, [[kingfisher]]s, [[otter]]s, [[raccoon]]s, [[skunk]], [[mink]], [[cat]]s, [[fox]]es, and [[Badger (animal)|badgers]] are all capable of spotting out koi and eating them.<ref name="theblogadventure.com"/> 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]] and a [[Koi pond|filtration]] 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.<ref>{{Cite web |last=Doctor |first=Atsushi Ueno |date=18 December 2023 |title=Instructions for training koi fish to eat from your hand |url=https://zenkoifarm.vn/cach-tap-cho-ca-koi-an-tren-tay/ |access-date=9 February 2024 |website=Zen Koi Garden Research Center |language=vi |archive-date=16 May 2024 |archive-url=https://web.archive.org/web/20240516033040/https://zenkoifarm.vn/cach-tap-cho-ca-koi-an-tren-tay/ |url-status=live }}</ref> 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 {{convert|10|°C|°F|abbr=on}}.<ref>{{cite web |url=http://www.lagunakoi.com/Koi-Feeding-Guide-Library-sc-334.html |title=Koi Feeding Guide |work=lagunakoi.com |access-date=2 October 2013 |archive-date=27 January 2021 |archive-url=https://web.archive.org/web/20210127230658/http://www.lagunakoi.com/Koi-Feeding-Guide-Library-sc-334.html |url-status=dead }}</ref><ref>{{cite web |url=http://www.mitchkoi.co.uk/koikeepingtips/best-temperature-feed-koi-fish/ |title=Temperatures to feed koi fish |work=mitchkoi.co.uk |access-date=1 April 2014 |archive-date=13 April 2014 |archive-url=https://web.archive.org/web/20140413154722/http://www.mitchkoi.co.uk/koikeepingtips/best-temperature-feed-koi-fish/ |url-status=dead }}</ref> 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.<ref name="HuntingfordJobling2012">{{cite book |author1=Felicity Huntingford |author2=Malcolm Jobling |author3=Sunil Kadri |title=Aquaculture and Behavior |url=https://books.google.com/books?id=x9pnZqx7788C&pg=PA12 |date=2012 |publisher=John Wiley & Sons |isbn=978-1-4051-3089-9 |pages=12– |quote=... and there are reports of fish that have achieved ages of 100–200 years (Purdom 1993; Billard 1999). |access-date=3 November 2016 |archive-date=16 May 2024 |archive-url=https://web.archive.org/web/20240516033011/https://books.google.com/books?id=x9pnZqx7788C&pg=PA12#v=onepage&q&f=false |url-status=live }}</ref> One famous scarlet koi named "[[Hanako (fish)|Hanako]]" was owned by several individuals, the last of whom was Komei Koshihara. In July 1974, a study of the [[Identification of aging in fish#Scales|growth rings]] of one of the koi's scales reported that Hanako was 226 years old.<ref>{{cite news |url=https://www.theguardian.com/uk/2007/apr/12/animalwelfare.world |title=The Guardian |newspaper=The Guardian |date=12 April 2007 |access-date=11 April 2009 |location=London |first=Laura |last=Barton |archive-date=24 June 2018 |archive-url=https://web.archive.org/web/20180624093132/https://www.theguardian.com/uk/2007/apr/12/animalwelfare.world |url-status=live }}</ref> Some sources give an accepted age for the species at little more than 50 years.<ref>{{cite book |title=Animal Records |publisher=Sterling Publishing Company |author=Carwardine, Mark |author-link=Mark Carwardine |year=2008 |pages=201 |isbn=978-1-4027-5623-8}}</ref><ref>{{Cite web |url=http://genomics.senescence.info/species/entry.php?species=Cyprinus_carpio |title=AnAge entry for Cyprinus carpio |work=genomics.senescence.inf |access-date=24 October 2011 |archive-date=27 September 2011 |archive-url=https://web.archive.org/web/20110927072741/http://genomics.senescence.info/species/entry.php?species=Cyprinus_carpio |url-status=live }}</ref>

=== Disease ===
Koi are very hardy. With proper care, they resist many of the parasites that affect more sensitive tropical fish species, such as ''[[Trichodina]], [[Epistylis]]'', and ''[[Ichthyophthirius multifiliis]]'' 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<ref>{{Cite web |last=Doctor |first=Atsushi Ueno |date=18 December 2023 |title=Research On Khv Disease In Koi Fish |url=https://zenkoifarm.vn/kiem-soat-va-dieu-tri-benh-khv-o-ca-koi/ |access-date=9 February 2024 |website=Zen Koi Garden Research Center |language=vi |archive-date=16 May 2024 |archive-url=https://web.archive.org/web/20240516033046/https://zenkoifarm.vn/kiem-soat-va-dieu-tri-benh-khv-o-ca-koi/ |url-status=live }}</ref>) and [[rhabdovirus]] carpio, which causes [[spring viraemia of carp]] (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]] 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]] light. The vaccine has a 90% success rate<ref>[http://www.kovax.co.il/products/kv3-vaccine-against-khv/ "KV3 Vaccine against KHV"] {{Webarchive|url=https://web.archive.org/web/20170629202233/http://www.kovax.co.il/products/kv3-vaccine-against-khv/ |date=29 June 2017 }}. KoVax Ltd. – Specializes in Aqua culture vaccines development and Manufacturing.</ref> 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.<ref>Reynolds, Paula (October 2011) [http://www.mitchkoi.co.uk/media/In-Focus-KHV.pdf ISRAELI KOI ...and the battle against KHV] {{Webarchive|url=https://web.archive.org/web/20140323045303/http://www.mitchkoi.co.uk/media/In-Focus-KHV.pdf |date=23 March 2014 }}. mitchkoi.co.uk</ref> Only [[biosecurity]] measures such as prompt detection, [[Isolation (health care)|isolation]], and [[disinfection]] 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]], 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.<ref>[https://web.archive.org/web/20131004225841/http://www.sfbakc.org/Articles/SVC_Impact.htm Spring Viremia of Carp]. Impact Worksheet•17 July 2002</ref><ref>[http://koisale.com/inprogress2/ourkoi.php "Blackwater Creek Koi Farms"] {{Webarchive|url=https://web.archive.org/web/20150321072753/http://www.koisale.com/inprogress2/ourkoi.php |date=21 March 2015 }}. ''koisale.com''.</ref>

== Breeding ==
{{Unreferenced section|date=January 2024}}[[File:Koi feeding, National Arboretum.jpg|thumb|right|Feeding of a large school]]
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 [[Asian arowana|arowana]] 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''<ref>{{Cite web |last=Doctor |first=Atsushi Ueno |date=5 December 2023 |title=Research On Tosai Koi Fish |url=https://zenkoifarm.vn/ca-koi-tosai-la-gi/ |access-date=9 February 2024 |website=Zen Koi Garden research center |language=vi |archive-date=16 May 2024 |archive-url=https://web.archive.org/web/20240516033050/https://zenkoifarm.vn/ca-koi-tosai-la-gi/ |url-status=live }}</ref>), 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 ==
[[File:Koi Feeding in Mt Qingxiu Nanning Close.JPG|right|thumb|Various colors of koi feeding in a pond in Qingxiu Mountain, [[Nanning, China]]]]
{{See also|Cyprinus rubrofuscus}}

Koi have been accidentally or deliberately released into the wild in every continent except [[Antarctica]]. They quickly revert to the natural coloration of an Amur carp within a few generations. In many areas, they are considered an [[invasive species]] and a [[Pest (organism)|pest]]. In the states of [[Queensland]] and [[New South Wales]] in Australia, they are considered noxious fish.<ref>[http://www.daff.qld.gov.au/fisheries/pest-fish/noxious-fish/carp "Carp"] {{Webarchive|url=https://web.archive.org/web/20150328082433/https://www.daff.qld.gov.au/fisheries/pest-fish/noxious-fish/carp |date=28 March 2015 }}. ''daff.qld.gov.au''.</ref><ref>{{Cite web |date=August 2014 |title=Freshwater pest fish in New South Wales |url=http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0007/369106/Freshwater-pest-fish-in-nsw.pdf |website=NSW Department of Primary Industries |access-date=6 April 2022 |archive-date=19 June 2022 |archive-url=https://web.archive.org/web/20220619010704/http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0007/369106/Freshwater-pest-fish-in-nsw.pdf |url-status=live }}</ref>

In Japan, koi releases are sometimes held as an event for tourism purposes. However, as koi is artificial breed, this causes [[genetic pollution]] by breeding with native carps.<ref>{{Cite journal |date=2017 |title=「第 3 の外来魚問題」－人工改良品種の野外放流をめぐって－の開催報告 |url=https://repository.kulib.kyoto-u.ac.jp/dspace/bitstream/2433/245556/1/jji_64_233.pdf |journal=Japanese Journal of Ichthyology |volume=64 |issue=2 |pages=233-236}}</ref>

Koi 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.<ref>[https://nas.er.usgs.gov/queries/factsheet.asp?speciesID=4 "Common Carp (''Cyprinus carpio'') – FactSheet"] {{Webarchive|url=https://web.archive.org/web/20090510183452/http://nas.er.usgs.gov/queries/FactSheet.asp?speciesID=4 |date=10 May 2009 }}. ''usgs.gov''.</ref>

In many areas of North America, koi are introduced into the artificial "[[water hazard]]s" and ponds on golf courses to keep water-borne insect larvae under control through predation.

== In common culture ==
[[File:Nagaoka Koi Show 05.jpg|thumb|61st Nagaoka Koi Show at [[Yamakoshi, Niigata|Yamakoshi]] Branch Office, Nagaoka, [[Niigata Prefecture]], Japan]]

In Japan, the koi is a symbol of [[luck]], [[prosperity]], and [[Luck|good fortune]], and also of [[psychological resilience|perseverance]] in the face of adversity.<ref>{{cite web |last1=Staff |first1=Inked Mag |title=An Inked Guide to Symbolism Within Japanese Tattoos |url=https://www.inkedmag.com/original-news/japanese-tattoo-symbolism |website=Tattoo Ideas, Artists and Models |date=9 November 2020 |access-date=16 December 2020 |language=en |archive-date=28 November 2020 |archive-url=https://web.archive.org/web/20201128022122/https://www.inkedmag.com/original-news/japanese-tattoo-symbolism |url-status=live }}</ref> Ornamental koi are symbolic of [[Culture of Japan|Japanese culture]] and are closely associated with the country's national identity.<ref>{{cite web |last1=Azuma |first1=Mariko |title=The Men of Koiyama: Keeping the Gion Festival Tradition for the Next Generation |url=https://japan-forward.com/the-men-of-koiyama-keeping-the-gion-festival-tradition-for-the-next-generation/ |website=JAPAN Forward |access-date=16 December 2020 |date=21 August 2020 |archive-date=26 January 2021 |archive-url=https://web.archive.org/web/20210126084716/https://japan-forward.com/the-men-of-koiyama-keeping-the-gion-festival-tradition-for-the-next-generation/ |url-status=live }}</ref> The custom of ''[[koinobori]]'' (carp streamers), which began in the [[Edo period]] (1603–1867), is still practiced today and displayed in gardens on [[Children's Day (Japan)|Children's Day]], 5 May.<ref name="yurai">{{cite web|url=https://www.touken-world.jp/tips/75943/|archive-url=https://web.archive.org/web/20230204195601/https://www.touken-world.jp/tips/75943/|script-title=ja:五月人形と鯉のぼりの由来|language=ja|publisher=Nagoya Japanese Sword Museum Nagoya Touken World|archive-date=4 February 2023|access-date=4 February 2023}}</ref>

In Chinese culture, the koi represents fame, [[Filial piety|family harmony]], and [[wealth]]. It is a [[feng shui]] favorite, symbolizing abundance as well as perseverance and strength, and has a mythical potential to transform into a [[Dragon#China|dragon]].<ref>{{cite news |last1=Pinghui |first1=Zhuang |title=What's with China's internet users and this fish? |url=https://www.scmp.com/news/china/society/article/2171547/whats-chinas-internet-users-and-fish |access-date=16 November 2022 |work=South China Morning Post |date=4 November 2018 |language=en |archive-date=16 November 2022 |archive-url=https://web.archive.org/web/20221116222851/https://www.scmp.com/news/china/society/article/2171547/whats-chinas-internet-users-and-fish |url-status=live }}</ref> Since the late 20th century, the keeping of koi in outdoor [[water garden]]s has become popular among the more affluent Chinese. [[Koi pond]]s are found in Chinese communities around the world, and the number of people who keep koi imported from [[Niigata (city)|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.<ref name = "gendai1">''[https://web.archive.org/web/20200615042741/https://gendai.ismedia.jp/articles/-/63682 The reason why wealthy Chinese started to buy a lot of Japanese "nishikigoi" 1/3]'', Gendai Business.  29 March 2019.</ref><ref name = "gendai3">''[https://web.archive.org/web/20190331211816/https://gendai.ismedia.jp/articles/-/63682?page=3 The reason why wealthy Chinese started to buy a lot of Japanese "nishikigoi" 3/3]'', Gendai Business. 29 March 2019.</ref>

Koi are also popular in many countries in the equatorial region, where outdoor water gardens are popular.<ref>{{cite news |title=Japan's Koi fish gaining popularity around world |url=https://www.aninews.in/news/world/asia/japans-koi-fish-gaining-popularity-around-world20200525181855/ |access-date=16 December 2020 |work=ANI News |publisher=ANI |language=en |archive-date=28 September 2020 |archive-url=https://web.archive.org/web/20200928163402/https://aninews.in/news/world/asia/japans-koi-fish-gaining-popularity-around-world20200525181855/ |url-status=live }}</ref> In [[Sri Lanka]], interior courtyards most often have one or several fish ponds dedicated to koi.<ref>{{cite web |title=The detail: koi fish pond, Sri Lanka {{!}} The Voyageur |url=http://thevoyageur.net/2014/12/05/the-detail-koi-fish-pond-sri-lanka/ |website=thevoyageur.net |access-date=1 January 2019 |archive-date=2 July 2018 |archive-url=https://web.archive.org/web/20180702095247/http://thevoyageur.net/2014/12/05/the-detail-koi-fish-pond-sri-lanka/ |url-status=live }}</ref>
{{Clear}}

== See also ==
* [[Culture of Japan]]
* [[Japanese aesthetics]]
* [[Japanese white crucian carp]]
{{clear}}

== References ==
{{Reflist}}

== Further reading ==
* {{Cite book |author=George C. Blasiola |title=Koi: everything about selection, care, nutrition, diseases, breeding, pond design and maintenance, and popular aquatic plants |location=[[Hauppauge, New York]] |publisher=[[Barron's Educational Series]] |year=1995 |isbn=978-0-8120-3568-1}}
* {{Cite book |author=David Twigg |title=How to Keep Koi |location=New York |publisher=[[Howell Book House]] |year=2001 |isbn=978-0-7645-6242-6}}
* {{Cite book |author=Nicholas Saint-Erne |title=Advanced Koi Care |location=Glendale, AZ |publisher=[[Erne Enterprises]] |year=2010 |isbn=978-1-59247-400-4}}

== External links ==
{{Commons category}}
{{Wiktionary}}
* [https://web.archive.org/web/20060920140711/http://www.cosmosmagazine.com/node/100 Feature article on treating sick fish, especially koi, "Surgery to Scale," ''Cosmos Magazine'']
* [https://www.niwa.co.nz/our-science/freshwater/tools/fishatlas/species/koi_carp Koi in the NIWA Atlas]

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[[Category:Carp]]
[[Category:Fish of Japan]]
[[Category:Articles containing video clips]]
[[Category:National symbols of Japan]]