Koi Terminology Guide
Walk into any koi dealer, open a Japanese auction list, or watch a breeder video and it can feel like you’ve accidentally tuned into a different language. Tosai, nisai, beni, sumi, kiwa, tategoi… and everyone around you is nodding like it’s obvious.
This glossary exists for one simple reason: to stop koi keeping feeling like a secret club.
We could translate everything into plain English. “Red, Black, Edge of the pattern, Young fish.” But instead, koi keeping leans on Japanese terminology, and there’s something quietly poetic about that. The language of the people who shaped Nishikigoi is still the language we use today, whether we’re stood in a Niigata mud pond or a back garden in Yorkshire.
Japanese terminology is baked into this hobby. It’s part of the history and part of what makes koi shows, breeding and judging work. But for newcomers and even for seasoned keepers, it can be confusing when words are used without explanation.
So this is a straight-up Koi Terminology Guide. No mystique. Hopefully clear meanings for the words you’ll actually hear when buying koi, watching shows, or talking with breeders and dealers.
Bookmark it. Come back to it. And the next time someone says “nice kiwa but the beni’s still developing”, you’ll know exactly what they mean.
Koi Age Terms
Tosai
A koi in its first year of life, up to around 12 months old.
This is the age most small koi are sold at, and where potential is judged rather than finished quality.
Nisai
A koi in its second year of life, roughly 12 to 24 months old.
This is when body shape starts to develop and colour begins to stabilise.
Sansai
A koi in its third year of life, around 2 to 3 years old.
Patterns and skin quality become much clearer, and serious show prospects start to separate themselves.
Yonsai
A koi in its fourth year of life, around 3 to 4 years old.
Body volume and balance improve, and high-grade koi start to look “adult”.
Gosai
A koi in its fifth year of life, around 4 to 5 years old.
Often considered mature koi, especially in Japanese terms.
Rokusai
A koi in its sixth year of life, around 5 to 6 years old.
Nanasai
A koi in its seventh year of life, around 6 to 7 years old.
Hassai
A koi in its eighth year of life.
Kyusai
A koi in its ninth year of life.
Jussai
A koi in its tenth year of life.
After Jussai, koi are often just referred to by their actual age rather than a specific term, for example “12-year-old koi” or “15-year-old koi”.
Extra useful terms tied to age
Tategoi
A koi kept for future development, usually Tosai or Nisai with strong potential.
Oyagoi
Breeding koi, usually mature Gosai and older.
Chigyo
Fry or very young baby koi before being graded.
A-Z GUIDE
A
Ago Sumi
Black pigment appearing around the gill plates.
Ai
Blue or indigo colour.
Ai Goromo
Koromo-type koi where the red scales are edged in blue, giving a netted look.
Ai Showa
Showa koi showing blue tones in the sumi.
Aizumi
Black pigment with an indigo tint.
Aka
Solid red body colour.
Aka Bekko
Red koi with black markings.
Aka Hajiro
Red koi with white fin tips.
Akamuji
Single-colour light red koi.
Akame
Red iris, common in Kigoi and albino lines.
Aka Matsuba
Red koi with pinecone-style scale reticulation.
Aka Sanke
Sanke dominated by red over most of the body.
Albino
Koi lacking pigment, usually with red eyes.
Ami
Net pattern.
Amime
Mesh-like scale effect.
Aragoke
Large armour-style scales.
Arashi Kumo
Storm-cloud pattern formed by layered sumi and shadow.
Asagi
Blue-grey koi with reticulated scales and red on cheeks and sides.
Atama
Top of the head.
Ato Sumi
Sumi that develops later in life.
B
Bekko
Solid base colour koi with black markings (Shiro, Aka or Ki Bekko).
Beni
Deep red pigment.
Beni Kumonryu
Kumonryu with red markings.
Benigoi
Non-metallic deep red koi.
Beta Gin
Highest grade of sparkling scale.
Bire
Red patterning on Asagi and Shusui.
Boke
Weak or unfinished sumi.
Bozu
No red on the head.
Budo
Clustered grape-like pattern.
Budo Goromo
White koi with purple-toned clusters.
Budo Sanke
Budo pattern mixed with Sanke markings.
C
Cha
Brown colour.
Chagoi
Brown koi known for growth and tame behaviour.
Chigyo
Unsorted fry.
Chrysanthemum Pattern
Circular clustered pattern resembling flower petals.
Caudal Fin
Tail fin.
D
Dagoi
Poor quality koi.
Dangara
Stepped pattern.
Danmoyo
Step-style pattern.
Doh
Body.
Doh Hi
Red on the body.
Doh Zumi
Black on the body.
Doitsu
Scaleless or partially scaled koi.
Doitsu Kujaku
Metallic doitsu koi with reticulation only on scale rows.
Doitsu Yamato Nishiki
Scaleless metallic Sanke.
Doware
Large white break in a pattern.
E
Enyu
Doitsu koi with white body and red pattern and metallic mirror scales.
Etsu No Hisoku
Yellow-green doitsu koi.
F
Flowery Kohaku
Kohaku with many small red islands.
Fukarin
Metallic brightness around scale edges.
Fukurin
Reticulated “frame” around scales
G
Gaku Hi
Red on the forehead.
Gin
Silver metallic shine.
Gin Matsuba
Metallic koi with pinecone reticulation.
Gin Rin
Sparkling scale type.
Ginrin Showa
Showa with glittering scales.
Gosanke
Kohaku, Sanke and Showa.
Goshiki
Five-colour koi with layered pigment.
H
Hachi
Head.
Hachiwari
Lightning stripe on the head.
Hada
Skin quality.
Hajiro
Black koi with white fin tips.
Hanatsuki
Red extending down the nose.
Hara
Abdomen.
Hariwake
Two-colour metallic koi (platinum + yellow/orange).
Hi
Red pigment.
Higoi
Red koi group (Benigoi, Akamuji).
Hikari
Metallic.
Hikarimono
Single-colour metallic koi (Ogon group).
Hikarimoyo
Multi-coloured metallic koi.
Hirenaga
Longfin or butterfly koi.
Hoshi
Window inside a pattern.
I
Ichimatsu
Checkerboard pattern.
Inazuma
Lightning-shaped pattern.
Ippon Hi
Continuous red from head to tail.
Iromono
Group term for non-white-based koi.
J
Jari
Gravel.
Jihada
Skin texture.
K
Kabuto
Head colour different from body.
Kage (Sumi)
Shadow or secondary pigment.
Kamisori
Razor-sharp pattern edge.
Kanoko
Dappled red on individual scales.
Karasu
Solid black koi.
Kasane Sumi
Black appearing on red.
Katamoyo
Pattern mostly on one side.
Kawarimono
All non-metallic koi not in standard classes.
KHV
Koi herpes virus.
Ki
Yellow.
Ki Bekko
Yellow koi with black markings.
Ki Utsuri
Black koi with yellow pattern.
Kigoi
Yellow koi.
Kikusui
Metallic doitsu Hariwake.
Kin
Gold metallic colour.
Kin Gin Rin
Metallic sparkling scales.
Kin Showa
Metallic Showa.
Kin Ki Utsuri
Metallic Ki Utsuri.
Kohaku
White koi with red pattern.
Koromo
Red pattern edged in darker pigment.
Kuchi
Mouth.
Kujaku
Metallic reticulated koi with red or gold pattern.
Kumonryu
Black doitsu koi with changing white markings.
Kuro
Black.
Kurogoi
Wild black carp ancestor.
Kurozumi
Deep glossy black.
L
Leather Koi
Completely scaleless koi.
Longfin Koi
Butterfly koi varieties of standard types.
M
Mado
Window in a pattern.
Magoi
Wild carp ancestor.
Maruten
Single head marking plus body pattern.
Maruzome
Rounded pattern edge following scale shape.
Matsuba
Pinecone reticulation pattern.
Menkaburi
Red covering the entire head.
Menware
Lightning stripe across head.
Midori
Green.
Midorigoi
Green doitsu koi.
Motoguro
Black at fin joints.
Muji
Single-colour koi.
N
Narumi
Medium blue tone.
Nidan
Two-step pattern.
Nishikigoi
Ornamental koi.
Nosezumi
Black overlapping red.
O
Ochiba Shigure
Grey koi with brown pattern resembling autumn leaves.
Odome
Last pattern before the tail.
Ogon
Metallic koi group (Yamabuki, Platinum, Orenji, etc.).
Ojime
Gap before tail pattern.
Omoyo
Single wrapping pattern.
Orenji
Orange colour.
Oyagoi
Parent koi.
P
Platinum Ogon
Solid metallic white koi.
Purachina
Platinum metallic koi.
R
Renzokumoyo
Continuous pattern.
Reticulation
Net-like scale pattern.
S
Sabi
Depth of skin appearance.
Sandan
Three-step pattern.
Sanke
White koi with red and black markings.
Sansai
Three-year-old koi.
Sarasa
Longfin patterned koi.
Sashi
Soft leading edge of a pattern.
Shimi
Small black freckles.
Shiro
White.
Shiro Bekko
White koi with black markings.
Shiro Utsuri
Black koi with white markings.
Shiroji
White skin.
Showa
Black-based koi with red and white.
Shusui
Doitsu Asagi with red markings.
Sokozumi
Faint underlying sumi.
Soragoi
Grey koi.
Sumi
Black pigment.
Sumi Goromo
Koromo with black reticulation.
Suminagashi
Black koi with white reticulation.
T
Taikei
Body shape and structure.
Tancho
Single red spot on the head.
Tategoi
Koi with future potential.
Tebire
Pectoral fin.
Teri
Gloss.
Tosai
First-year koi.
Tora Ogon
Metallic yellow koi with black markings.
Tsubo Sumi
Black on white skin.
U
Umebachi
Apricot flower-shaped marking.
Urushi Zumi
Jet-black glossy sumi.
Utsuri
Black koi with white, red or yellow pattern.
V
Vermin
Predators of koi.
W
Wabi
Depth and refinement of skin.
Wagoi
Fully scaled koi.
Y
Yamabuki Ogon
Metallic golden yellow koi.
Yondan
Four-step pattern.
Yonsai
Four-year-old koi.
Yotsushiro
Black koi with white head, fins and tail.
Z
ZNA
Zen Nippon Airinkai, international koi organisation.
