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Scales and skin

By the koi.wiki editorial team · Updated

Key facts:
Like other cyprinids, koi are covered by cycloid scales, a type of fish scale common to salmon and carp, which grow from the dermis and can provide protection and camouflage[6]. In nishikigoi, scale pattern and texture are treated as a distinct axis of classification alongside color and pattern, producing categories such as wagoi (fully scaled), doitsugoi (sparsely scaled), kagami-goi or mirror koi, yoroi or armor koi, and kinginrin (metallic, sparkling scales)[2][1].These scale types can occur across many color varieties — for example Doitsu versions exist of Kohaku, Sanke, and Showa[1], and ginrin versions exist of almost all other varieties[2][3].

Wagoi (fully scaled koi)

Wagoi (和鯉) is the term used in Japan for common nishikigoi that have scales covering almost the entire body, as opposed to Doitsugoi, which have little or no scale coverage[1]. The All Japan Nishikigoi Promotion Association (JNPA) explicitly contrasts Wagoi, described as koi with scales covering almost the entire body, with Doitsugoi, which arose from crossbreeding Japanese nishikigoi with a nearly scaleless carp bred for food in Eastern Europe, including Germany[1]. The organization Shinkokai USA, affiliated with the JNPA, likewise lists Wagoi and Doitsugoi as separate scale-type categories within its variety listing[7][8].Doitsu-goi (ドイツ鯉) originated from crossbreeding established koi varieties with German carp that generally had only a single line of scales along each side of the dorsal fin[2]. According to the JNPA, Doitsugoi have almost no scales on the body and the skin is exposed, with varieties such as Doitsu-kohaku, Doitsu-taisho-sanshoku, and Doitsu-showa-sanshoku showing the color patterns of their scaled counterparts but with this reduced scaling[1]. The JNPA also states that Doitsugoi tend to show brighter, more vivid colors than fully scaled Wagoi, and that a good Doitsugoi has a clear boundary, called kiwa, between the skin color and the pattern[1].According to a secondary source, the US dealer Kodama Koi Farm, scaleless carp were originally developed in Germany for ease of cooking and were imported into Japan in 1904 as a food source, with a breeder named Mr. Kichigoro Akiyama credited with crossing scaleless carp with the Asagi variety to produce the first Doitsu koi[4][9]. Wikipedia states that four main Doitsu scale patterns exist: a row of scales along the dorsal fin only; a row running from the head-shoulder junction along the full body length; the same with an added lateral-line row of scales, known as mirror koi; and a rare, nearly fully armored type called armor koi, also known as Kagami-goi, or mirror carp[2].Kodama Koi Farm notes, as a commercial appreciation guide, that in Doitsu varieties the layout of remaining scales is itself judged, with irregular or out-of-place scales referred to as muda-goke, and that breeders reportedly find it easier to breed Doitsu with very few scales than to achieve a perfectly even scale layout[4]. The same source states that appreciation of a Doitsu koi also requires evaluating it against the standards of its underlying scaled variety, such as Hi and Shiroji quality in a Doitsu Kohaku[4].

Mirror koi (kagami-goi) and armor koi (yoroi)

Among Doitsu scale patterns, the variant with scales running along both the shoulder-to-tail line and the lateral line is referred to as mirror koi, while the rarest pattern, nearly or fully covered with large plate-like scales resembling armor, is called armor koi or Kagami-goi (鏡鯉, カガミゴイ), also translated as mirror carp[2].

Kinginrin (ginrin) scales

Kinginrin (金銀鱗) describes koi with metallic, glittering, metal-flake-appearing scales, a name that translates as “gold and silver scales” and is commonly abbreviated to ginrin[2]. Ginrin versions exist of almost all other koi varieties and are described by Wikipedia as fashionable, with their sparkling scales contrasting the smooth, even metallic skin of Ogon varieties[2]. The American Koi Judges Association (AKJA) similarly defines kinginrin as a normally scaled koi with gold or silvery mirror-like deposits on each scale, and notes that “ginrin” is the more commonly used term[10].The organization Zen Nippon Airinkai (ZNA) states that for show entry, ginrin scales should appear clearly in two, three, or more lines along both sides of the spine, and that fewer or scattered ginrin scales are judged insufficient for the Kinginrin category[3]. ZNA groups Ginrin Kohaku, Ginrin Sanke, Ginrin Showa, and Ginrin Utsuri together as Kinginrin Group 1, and lists regional styles of ginrin scale including Niigata styles such as kado-gin, sudare-gin, kasu-gin, tama-gin, pearl-ginrin, tsubu-gin, and beta-gin, and Hiroshima styles such as daiya-gin (diamond ginrin), chara-gin, and gacha-gin[3].According to the US dealer Kodama Koi Farm, Ginrin koi have diamond-like scales across the entire body that reflect and shine differently than metallic or platinum koi, with named variations including Beta Gin, where the whole scale shines, and Kado Gin, where only the scale edges are reflective, as well as Diamond and Pearl Ginrin[5]. The same source states that, for show purposes, Ginrin should display at least three rows of shimmering scales evenly from shoulder to tail with no missing scales[5].Fukurin is defined by the AKJA as the area of skin around the smaller scales of good metallic koi, where the smaller the scales, the greater the luster produced[10]. Related terms recorded by the AKJA include kokesuki, scales that are visible because the overlying color is thin, and madoaki, scales that show “shadows” under the skin[10]. ZNA’s body terminology glossary notes that kata, the shoulder area, is defined in part by the front row of the scales, indicating that scale rows are also used as anatomical reference points when describing koi body conformation[11].

Biology of fish scales

In fish generally, scales are small rigid plates that grow from the skin and can provide protection, camouflage through reflection and coloration, and possible hydrodynamic benefits[6]. Most bony fishes, a group that includes carp, are covered with cycloid scales (as in salmon and carp) or ctenoid scales (as in perch), which differ from the placoid scales of cartilaginous fishes such as sharks and rays[6]. Many teleost fish scales are also highly reflective, functioning as small mirrors through layered crystal structures, an optical effect behind the shimmering appearance described in ornamental scale types such as ginrin[6].

Common questions

What is the difference between wagoi and doitsu koi?
Wagoi (和鯉) refers to common koi with scales covering almost the entire body, while Doitsugoi have almost no scales and exposed skin, a trait that originated from crossbreeding with a nearly scaleless carp bred in Eastern Europe, including Germany[1].
What makes a koi a ginrin (kinginrin) koi?
Kinginrin describes koi with metallic, sparkling, or mirror-like scales, and for show purposes Zen Nippon Airinkai requires ginrin scales to appear clearly in at least two or three lines along both sides of the spine[2][3].
What is a mirror koi or armor koi?
These are Doitsu scale patterns: mirror koi have an added row of scales along the lateral line in addition to the dorsal rows, while armor koi (also called Kagami-goi, or mirror carp) are nearly or fully covered with large, plate-like scales[2].
What is fukurin on a metallic koi?
Fukurin is the skin area around the smaller scales of good metallic koi; smaller scales in this area are associated with greater luster[10].
Do all koi varieties come in doitsu or ginrin form?
According to the JNPA, Doitsu versions exist across many varieties including Kohaku, Showa, Goshiki, and Tancho forms, and Wikipedia notes that ginrin versions exist of almost all other koi varieties[1][2].

References

  1. ^ Doitsugoi - Variety - All Japan Nishikigoi Promotion Association. All Japan Nishikigoi Promotion Association. jnpa.info/en/nishikigoi/varieties/type/doitsugoi/. Retrieved November 2026.
  2. ^ Koi (Wikipedia). Wikipedia. en.wikipedia.org/wiki/Utsurimono. Retrieved November 2026.
  3. ^ KINGINRIN 1 | Zen Nippon Airinkai. Zen Nippon Airinkai. zna.jp/en/keep-nishikigoi/varieties-of-nishikigoi/kinginrin-1/. Retrieved November 2026.
  4. ^ Doitsu Variety - The beauty of Scaleless Koi, Unique Koi Varieties. Kodama Koi Farm (koi dealer). kodamakoifarm.com/doitsu-variety-beauty-no-scales/. Retrieved November 2026.
  5. ^ Ginrin - Koi for Sale and History - Kodama Koi Farm. Kodama Koi Farm (koi dealer). kodamakoifarm.com/variety/ginrin/. Retrieved November 2026.
  6. ^ Fish scale (Wikipedia). Wikipedia. en.wikipedia.org/wiki/Fish_scale. Retrieved November 2026.
  7. ^ Variety - Shinkokai USA Official Website. Shinkokai USA (JNPA). shinkokaiusa.com/variety. Retrieved November 2026.
  8. ^ Variety - All Japan Nishikigoi Promotion Association. All Japan Nishikigoi Promotion Association. jnpa.info/en/nishikigoi/varieties/. Retrieved November 2026.
  9. ^ Doitsu - Koi For Sale - Kodama Koi Farm. Kodama Koi Farm (koi dealer). kodamakoifarm.com/variety/doitsu/. Retrieved November 2026.
  10. ^ Glossary – American Koi Judges Association (AKJA). American Koi Judges Association. akjajudges.com/glossary/. Retrieved November 2026.
  11. ^ NISHIKIGOI TERMINOLOGY 1 BODY | Zen Nippon Airinkai. Zen Nippon Airinkai. zna.jp/en/keep-nishikigoi/nishikigoi-terminology/nishikigoi-termino…. Retrieved November 2026.