Every koi is the same species — Cyprinus rubrofuscus, the Amur carp — and every named type is a selectively bred colour variety, not a separate fish. Japanese breeders group these varieties into about 16 recognised classes, collectively called Nishikigoi. Knowing the class names makes buying far easier, because price tracks pattern quality within a class rather than colour alone.
The Big Three (Gosanke)
Three varieties dominate shows and account for most of the koi sold worldwide.
| Variety | Pattern | What judges look for |
|---|---|---|
| Kohaku | White body with red (hi) markings | Snow-white base, deep even red, crisp pattern edges, no red on the head below the eyes |
| Taisho Sanke (Sanke) | White body, red markings, small black (sumi) accents | Black confined above the lateral line, used sparingly to balance the red |
| Showa Sanshoku (Showa) | Black body with red and white markings | Wrapping black that runs through the head and into the pectoral fin joints |
The quickest way to tell a Sanke from a Showa: Sanke is a white fish with black added, Showa is a black fish with white and red added. Look at the head — Showa carries black on it, Sanke almost never does.
Main Koi Varieties
- Utsurimono — black koi with a single second colour: Shiro Utsuri (white), Hi Utsuri (red), Ki Utsuri (yellow).
- Bekko — solid base colour with black stepping-stone markings: Shiro, Aka and Ki Bekko.
- Asagi — blue-grey net-patterned scales along the back with red on the flanks, belly and fin bases. One of the oldest varieties.
- Shusui — the scaleless (Doitsu) version of Asagi, with a single row of dark scales along the dorsal line.
- Tancho — any variety with a single red spot on the head and no other red; Tancho Kohaku is the classic.
- Ogon / Hikarimuji — single-colour metallic koi: Yamabuki (yellow gold), Platinum (white), Orenji (orange).
- Hikari Moyo — multi-coloured metallics, including Kujaku (metallic with net pattern and red markings).
- Kumonryu — scaleless black-and-white koi whose pattern shifts with the seasons and can change entirely from year to year.
- Chagoi — plain brown or bronze, famously the tamest and fastest-growing variety; often bought deliberately to settle a nervous pond.
- Ochiba Shigure — blue-grey body with copper or bronze markings, described as autumn leaves on water.
- Goshiki — five-colour koi, a Kohaku pattern over a netted blue-grey base.
- Koromo — Kohaku pattern where each red scale carries a blue or black reticulated edge.
- Doitsu — not a colour class but a scale type: German mirror carp genetics giving a scaleless body with large scales along the lateral and dorsal lines. Any variety can be Doitsu.
- Ginrin — a scale finish, not a colour: individual scales sparkle. Also crosses every variety.
Koi Fish Colours: Black, White, Blue
Searches for a colour usually map onto a specific named variety:
| Colour wanted | Varieties to ask for |
|---|---|
| Black koi | Karasugoi (solid black), Kumonryu (black and white), Shiro Utsuri (black and white), Matsuba (black netting over a base colour) |
| White koi | Platinum Ogon (solid metallic white), Shiro Utsuri, Shiro Bekko |
| Blue koi | Asagi, Shusui, Soragoi (solid blue-grey), Ai Goromo (blue-edged red scales) |
| Yellow / gold koi | Yamabuki Ogon, Ki Utsuri, Ki Bekko |
| Orange / red koi | Orenji Ogon, Benigoi (solid red), Hi Utsuri |
| Brown / bronze koi | Chagoi, Ochiba Shigure |
Butterfly Koi
Butterfly koi — also called longfin or dragon koi — are ordinary koi carrying a longfin gene, developed in the United States from a cross with Indonesian longfin carp. Fins, barbels and tail grow long and flowing.
- Same body length as standard koi (24–36 in), so the same pond requirements apply.
- They are not recognised in traditional Japanese show classes, though many Western shows now judge them separately.
- The long fins are more prone to catching on rough hardscape and to fin rot in poor water.
- They read as slower and more graceful in the water, which is why they are popular in viewing ponds.
Ghost Koi
Ghost koi are a hybrid of a metallic Ogon koi with a wild or mirror carp, first bred in the UK in the 1980s. They show a metallic sheen — usually silver or gold — over a darker, plainer body.
- Hardy and fast-growing thanks to hybrid vigour; often the survivors in a difficult pond.
- Larger appetite and stronger foraging instinct than most ornamental koi, which can mean uprooted pond plants.
- Not Nishikigoi and not shown in koi classes; they are also usually far cheaper.
- Sometimes sold as pest fish for large ponds where colour matters less than resilience.
Choosing a Koi
- Watch it swim before you look at the pattern. Body shape, straight spine and confident swimming outrank colour every time.
- Check the skin for ulcers, raised scales, red streaks in fins, and the gill covers for rapid or one-sided movement.
- Expect the pattern to change. Buy the koi you like now; do not pay a premium for what a young fish might become.
- Buy from one source where possible and quarantine everything for 3–4 weeks regardless of the seller's reputation.
- Add a Chagoi. They tame quickly and the rest of the pond follows them to the surface at feeding time.
Frequently Asked Questions
What are the main types of koi fish?
Japanese breeders recognise about 16 varieties of Nishikigoi. The three most important are the Gosanke: Kohaku (white with red), Taisho Sanke (white with red and black) and Showa Sanshoku (black with red and white). Other common classes include Utsurimono, Bekko, Asagi, Shusui, Tancho, Ogon, Kumonryu and Chagoi.
What is a butterfly koi?
Butterfly koi, also called longfin or dragon koi, are standard koi carrying a longfin gene developed in the United States from a cross with Indonesian longfin carp. They reach the same 24-36 inch body length as ordinary koi and are not recognised in traditional Japanese show classes.
What is a ghost koi?
Ghost koi are a hybrid of a metallic Ogon koi with a wild or mirror carp, first bred in the UK in the 1980s. They are hardy, fast-growing and cheaper than Nishikigoi, with a metallic silver or gold sheen over a plainer body, but they are not shown as koi.
What is a black koi fish called?
A solid black koi is a Karasugoi. Black-and-white varieties include Kumonryu (scaleless, pattern changes with the seasons) and Shiro Utsuri. Matsuba koi carry black netting over a base colour.
Do koi fish change colour as they grow?
Yes. Koi patterns develop over the first three to four years and keep shifting afterwards - red can spread or recede, black usually deepens with age, and metallic finishes dull in poor water. Kumonryu change pattern seasonally as a matter of course.