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koi.wiki: the koi reference

By the koi.wiki editorial team · Updated

Key facts: Koi biology concerns the taxonomy, anatomy, growth, lifespan and behavior of nishikigoi (錦鯉), ornamental carp bred from the black carp of Japan[1], with koi classed by most recent authorities as Cyprinus rubrofuscus rather than the European Cyprinus carpio[1][2].

koi.wiki is a reference on nishikigoi: the varieties and how they are judged, keeping koi in ponds, water quality and health, and the shows and clubs that grew up around them. Each entry below is written from cited sources, listed in its References section.

Koi varieties

Koi varieties are named groups of nishikigoi distinguished by skin color, pattern, and scale type, with authorities such as Zen Nippon Airinkai (ZNA) and the All Japan Nishikigoi Promotion Association (JNPA) organizing over a hundred recognized forms into classification systems used for appreciation and show judging.[3][4]

Koi biology

Koi biology concerns the taxonomy, anatomy, growth, lifespan and behavior of nishikigoi (錦鯉), ornamental carp bred from the black carp of Japan[1], with koi classed by most recent authorities as Cyprinus rubrofuscus rather than the European Cyprinus carpio[1][2].

Koi breeding

Koi breeding is the deliberate spawning and selective rearing of nishikigoi (錦鯉), in which breeders pair chosen parent fish (oyagoi, 親魚), hatch large numbers of eggs, and cull the great majority of fry to isolate the rare individuals with desirable color and pattern[1][5].

History of koi

The history of koi (錦鯉, nishikigoi) traces selective breeding of color-mutant food carp in the Niigata snow country during the late Edo period to today's global export industry, with the Tokyo Taisho Exposition of 1914 marking the moment koi gained nationwide recognition[6][1].

Koi breeders and farms

Nishikigoi (錦鯉) breeders are producers who raise and select koi, concentrated historically in Niigata Prefecture but also active in Hiroshima, Okayama and elsewhere in Japan[7].

Buying koi

Buying koi involves choosing a reputable dealer or breeder, understanding age, size and origin terms, judging price against quality factors, and quarantining new fish before introducing them to an established pond.[8][9]

Koi ponds

A koi pond is a purpose-built body of water for keeping Nishikigoi (錦鯉), typically deeper and more heavily filtered than an ordinary garden pond so that the fish stay healthy and show their colors well.[10][11]

Koi pond equipment

Koi pond equipment refers to the pumps, filters, aerators, skimmers, bottom drains, heaters and treatment devices used to circulate and condition water in a koi pond[12][10].

Water quality

Water quality refers to the chemical and physical condition of pond water—including ammonia, nitrite, nitrate, pH, alkalinity, dissolved oxygen and temperature—that determines whether koi can thrive[13][14].

Feeding koi

Feeding koi involves providing a balanced, omnivorous diet adjusted for water temperature and life stage, using commercial pellets supplemented with occasional treats.[1][15]

Seasonal koi care

Seasonal koi care refers to adjusting feeding, water management and pond preparation as water temperature changes throughout the year, since koi metabolism, appetite and disease risk all shift with the seasons[16][17].

Koi health and disease

Koi health and disease is a broad topic covering how nishikigoi become sick, the role of stress and water quality, and the infectious and non-infectious conditions that affect koi, ranging from parasites and bacteria to viruses such as koi herpesvirus[18][19].

Predators of koi

Koi face predation risk from a range of birds and mammals, including herons, kingfishers, otters, raccoons, skunks, mink, cats, foxes and badgers, because their bright colors make them highly visible against pond water[1].

Koi laws and regulations

Koi keeping is subject to a patchwork of national and regional laws covering disease reporting, import and export permits, and restrictions on koi as a potentially invasive carp species, with requirements varying considerably by country and, within some countries, by state or province.[20][21]

Koi clubs and associations

Koi keeping is organized worldwide through national and international clubs and associations that run shows, train judges, and promote nishikigoi (錦鯉) appreciation, ranging from Japan's Zen Nippon Airinkai (ZNA) and All Japan Nishikigoi Promotion Association (JNPA) to national societies in the Netherlands, United States, United Kingdom, South Africa, and Australia.[22][23]

Koi shows

Koi shows are competitive exhibitions where nishikigoi (錦鯉) are judged on body shape, quality and pattern, held by hobbyist and breeder organizations in Japan and around the world.[9]

Koi vs goldfish

Koi (Cyprinus rubrofuscus, a domesticated form of Amur carp) and goldfish (Carassius auratus) are both ornamental members of the carp family Cyprinidae, but they are distinct species that differ in ancestry, body shape, barbels and typical size.[1][24]

Koi vs common carp and wild carp

Koi (錦鯉, nishikigoi) are selectively bred, color-patterned carp descended from wild carp populations, most closely associated with the magoi (真鯉, black carp) raised in Japan[25][1]. Common carp (Cyprinus carpio) is the wild or semi-domesticated form typically found in olive, bronze, or gray tones and used for food and sport fishing rather than ornamental display[26][27].

Glossary of koi terms

Common questions about koi

Image credits and licenses

Sources and references

About koi.wiki

References

  1. ^ Koi (Wikipedia). Wikipedia. en.wikipedia.org/wiki/Koi. Retrieved November 2026.
  2. ^ Cyprinus rubrofuscus (Wikipedia). Wikipedia. en.wikipedia.org/wiki/Cyprinus_rubrofuscus. Retrieved November 2026.
  3. ^ Varieties of Nishikigoi | Zen Nippon Airinkai. Zen Nippon Airinkai. zna.jp/en/keep-nishikigoi/varieties-of-nishikigoi/. Retrieved November 2026.
  4. ^ Kawarigoi - Variety - All Japan Nishikigoi Promotion Association. All Japan Nishikigoi Promotion Association. jnpa.info/en/nishikigoi/varieties/type/kawarigoi/. Retrieved November 2026.
  5. ^ ニシキゴイ (Wikipedia). Wikipedia (Japanese). ja.wikipedia.org/wiki/錦鯉. Retrieved November 2026.
  6. ^ The Birth and History of Nishikigoi - All Japan Nishikigoi Promotion Association. All Japan Nishikigoi Promotion Association. jnpa.info/en/nishikigoi/history/. Retrieved November 2026.
  7. ^ 日本の伝統文化・美意識の象徴、錦鯉を世界へ発信 | 地域・分析レポート - 海外ビジネス情報 - ジェトロ. JETRO. jetro.go.jp/biz/areareports/2025/ee7cac04ab0dfd5d.html. Retrieved November 2026.
  8. ^ How to Select Koi - Which are Best to Choose for My Pond?. Kodama Koi Farm (koi dealer). kodamakoifarm.com/how-to-select-koi-for-pond/. Retrieved November 2026.
  9. ^ Q&A - All Japan Nishikigoi Promotion Association. All Japan Nishikigoi Promotion Association. jnpa.info/en/qa/. Retrieved November 2026.
  10. ^ Koi pond (Wikipedia). Wikipedia. en.wikipedia.org/wiki/Koi_pond. Retrieved November 2026.
  11. ^ Koi (Wikipedia). Wikipedia. en.wikipedia.org/wiki/Nishikigoi. Retrieved November 2026.
  12. ^ How to keep Nishikigoi - All Japan Nishikigoi Promotion Association. All Japan Nishikigoi Promotion Association. jnpa.info/en/nishikigoi/breeding/how-to/. Retrieved November 2026.
  13. ^ UF/IFAS EDIS FA099: Fish Health Management Considerations in Recirculating Aquaculture Systems—Part 1. University of Florida IFAS Extension (EDIS). ask.ifas.ufl.edu/publication/FA099. Retrieved November 2026.
  14. ^ Pond Water Quality Management and Testing for Healthy Koi. Kodama Koi Farm (koi dealer). kodamakoifarm.com/pond-water-quality-management-testing/. Retrieved November 2026.
  15. ^ SRAC Publication No. 5003: Principles of Fish Nutrition. Southern Regional Aquaculture Center. srac.msstate.edu/pdfs/Fact%20Sheets/5003%20Principles%20of%20Fish%2…. Retrieved November 2026.
  16. ^ How to Grow Big Koi: Guide to Large Koi Growth with a Healthy Pond. Kodama Koi Farm (koi dealer). kodamakoifarm.com/how-to-grow-big-koi/. Retrieved November 2026.
  17. ^ How Long Do Koi Fish Live? What is Lifespan & Growth?. Kodama Koi Farm (koi dealer). kodamakoifarm.com/how-long-do-koi-fish-live/. Retrieved November 2026.
  18. ^ UF/IFAS EDIS FA004: Introduction to Fish Health Management. University of Florida IFAS Extension (EDIS). ask.ifas.ufl.edu/publication/FA004. Retrieved November 2026.
  19. ^ UF/IFAS EDIS FA005: Stress—Its Role in Fish Disease. University of Florida IFAS Extension (EDIS). ask.ifas.ufl.edu/publication/FA005. Retrieved November 2026.
  20. ^ Importing or moving live fish and shellfish - GOV.UK. UK Government. gov.uk/guidance/importing-or-moving-live-fish-and-shellfish. Retrieved November 2026.
  21. ^ Noxious Aquatic Species in Victoria (Victorian Fisheries Authority). Victorian Fisheries Authority. vfa.vic.gov.au/operational-policy/pests-and-diseases/noxious-aquati…. Retrieved November 2026.
  22. ^ What’s ZNA | Zen Nippon Airinkai. Zen Nippon Airinkai. zna.jp/en/about-en/. Retrieved November 2026.
  23. ^ About All Japan Nishikigoi Promotion Association - All Japan Nishikigoi Promotion Association. All Japan Nishikigoi Promotion Association. jnpa.info/en/about/. Retrieved November 2026.
  24. ^ SRAC Publication No. 7201: Species Profile: Koi and Goldfish. Southern Regional Aquaculture Center. srac.msstate.edu/pdfs/Fact%20Sheets/7201%20Species%20Profile-%20Koi…. Retrieved November 2026.
  25. ^ What is a Nishikigoi? - Koi Fish History Explained and Meaning. Kodama Koi Farm (koi dealer). kodamakoifarm.com/what-is-nishikigoi-history-meaning/. Retrieved November 2026.
  26. ^ Koi vs Carp: Difference Between Koi and Carp. Kodama Koi Farm (koi dealer). kodamakoifarm.com/koi-vs-carp/. Retrieved November 2026.
  27. ^ Common carp (Wikipedia). Wikipedia. en.wikipedia.org/wiki/Common_carp. Retrieved November 2026.