koi fish varieties
There are 13 primary categories of Koi, and hundreds of varieties within those categories. The major named koi fish varieties include, but are not limited to the following (see descriptions below image):
Kohaku - White-skinned Koi, with a red pattern
Taisho Sanshoku (Sanke) - White-skinned Koi with a red and black pattern
Showa Sanshoku (Showa) - Black-skinned Koi with a red and white pattern
Tancho - Any koi with the only red being in a circle on its forehead. The fish can be a Tancho Showa, Tancho Sanke, or even Tancho Goshiki
Asagi - Koi with light blue scales on its top and red scales on its bottom
Shusui - The partially scaled version of an Asagi
Bekko - White, red, or yellow-skinned Koi with a black pattern
Utsurimono - Black Koi with a red, white, or yellow pattern
Goshiki - Mostly black Koi with red, white, brown and blue accents
Ogon - Koi that is one solid color; Can be regular or metallic; Known colors are red, orange, platinum, yellow and cream
Kin Gin Rin - Koi with shiny scales. The name translates into English as "Gold Silver Scales"; There are also Gin Rin versions of almost any other type of koi.
Kawarimono (Kawarigoi) - Miscellaneous types of Koi
Doitsu-goi - German Carp
Koromo - Koi with areas of blue-edged scales aligned neatly
Hikari-Moyomono - Koi with colored patterns over a metallic base, as well as koi in two metallic colours
Ghost Koi - "Hybrid" of Ogon and wild carp. Not Nishikigoi
Butterfly Koi - Long-finned version of all others. Not Nishikigoi