The cornerstone of koi and the most popular variety in Japan, Kohaku are white (shiro) Koi with red (hi) markings . Ideally the red markings should be deep in colour and uniform shade with the edges of the pattern well defined. It can’t be stressed enough that the white should be pure bright white and also free from blemishes. As a general guide, the red markings should cover about half of the body but may be distributed in many different ways.
More commonly known as Sanke, are three coloured Koi with red and black (sumi) markings on a white background. A good Sanke must have a pure white background and uniform red and black markings. There should be no black markings on the head. The body should have large red markings complimented by an even distribution of smaller black sumi.
Typically called Showa, these are the last of the Big Three varieties (Kohaku, Sanke, Showa) Showa are three coloured koi with red, black and white. Showa are similar to Sanke, however they have black markings (sumi) that extend below the lateral line and typically have sumi on the head. Showa are actually black fish with red and white markings. Traditional showa have red as the dominant colour with black and white in equal proportions, however modern showa tend to have more white.
Often referred to simply as Ogon, these are single colour koi with a metallic sheen. This variety includes standard and scaleless (Doitsu) koi. The most popular colours are platinum ogon and yellow ogon (Yamabuki). Also included are Matsuba Ogon, which have black colouration in the scales giving the fish a ‘pinecone’ effect. For people new to the hobby and experienced collectors as well, these fish are often very appealing because the bright colours are highly visible in the pond.
The Utsurimono (Utsuri) variety is comprised of 3 different two-colour koi. The Shiro Utsuri (black & white) is the most popular followed by the Hi Utsuri (red & black) and Ki Utsuri (yellow & black). Utsuri are black fish with either red white or yellow makings. Utsuri are sometimes confused with Bekko, however Bekko do not usually have any sumi (black) on the head, or below the lateral line
Asagi and Shusui are the two koi that have blue colouration. Asagi are fully scaled, non metallic, while the Shusui are similar in colour but they are Doitsu (no scales, or with a few rows of enlarged scales). Asagi typically have pale blue scales covering the top half of the body, and rusty red below. The head is preferably white but sometimes tends toward grey.
Koromo is class of koi that includes several varieties such as Goromo & Goshiki, Koromo literally means ‘robed’ in Japanese, which refers to the scales being outlined or ‘robed’ in a darker colour. The most popular is the Ai Goromo which similar to a Kohaku, but the red scales are lined with black.
A classic Tancho is thought of as a pure white fish with a perfectly round red marking on its head, however Tancho Sanke and Tancho Showa are also included in the classification. A perfectly round red pattern is the most sought after, but any symmetrical shape such as a flower or heart shape is acceptable as well.The ideal pattern should be confined to the head and may not touch or extend over the eyes, lips, cheeks, or shoulder. Its position must be in perfect balance to the head
Bekko are similar to Utsuri in that they are two-coloured koi and have 3 colours in the variety, Shiro Bekko (white & black), Aka Bekko (red & black) and Ki Bekko (yellow and Black). They differ from Utsuri because the do not typically have any sumi (black) on the head or below the lateral line.
Hikari Mono are metallic koi with more than 1 colour that do not fit into any other category. They immediately catch the attention of anyone who sees then because of their metallic sheen as well as their contrast in colour. Some of the more popular varieties include Hariwake, Kujaku, Yamatonishiki, Kikusui and Kikokuryu
Kin-gin-rin or commonly referred to as gin-rin koi are koi that have scales that sparkle. These days, basically any variety of koi is available with gin-rin scales, such as Showa, Kohaku, Chagoi, we have even seen some even some Doitsu arriving lately with their mirror /enlarged scales with gin-rin.
Shusui are similar to Asagi in colour, but they have the unique characteristic of being Doitsu (no scales, or with a few rows of enlarged scales). The typical colouration is pale blue body with two rows of large dark blue mirror scales running along the dorsal fin, and a single row running along the lateral line. The bottom half of the body is usually red and the head white. There are variations in Shusui such as, the Hi Shusui which has the body all or mostly red, Hana Shusui which has white replacing the blue on the top half of the body and also the Ki Shusui in which yellow replaces the blue and red on the body.
Kawarimono is basically a catch-all class for non metallic koi that don’t fit neatly into any other class. Kawarimono does include doitsu koi as well as gin-rin (reflective scale) koi. Some common varieties are Benigoi (plain solid orange), Kigoi (solid yellow – non metallic), Karasu (black or black and white) Chagoi (variations of brown), Soragoi (grey) and Ochiba (brown & grey pattern)