Shusui (秋翠 (Shūsui))
The Doitsu (scaleless) form of Asagi — a line of large blue scales along the back with red flanks.
Shusui: Rows of large dark-blue scales along the dorsal line and lateral line on otherwise smooth skin; red below.
| Pattern (JAS-aligned) | Rows of large dark-blue scales along the dorsal line and lateral line on otherwise smooth skin; red below. |
|---|---|
| Colours | Blue scale-lines on smooth skin, red-orange flanks and belly. |
| How to tell it | Smooth skin plus one or two neat rows of oversized blue scales — that combination is Shusui. |
The variety in Japanese koi culture
Shusui — the name evokes clear autumn water — was created by crossing Asagi with the German mirror carp, the same cross that produced the Doitsu scale type explained on the Doitsu page. The result keeps Asagi's blue-and-red scheme but redraws it as bold lines of enlarged scales on bare skin, so the fish reads as graphic and modern next to its fully scaled parent. The neatness of the scale rows and the cleanliness of the skin between them are what judges and keepers look at first.
Keeping notes on this page are limited to generally published principles about the variety in Japan. This page gives no diagnosis, no treatment and no prescription for an individual pond or fish. For a fish that looks unwell, contact a veterinarian or your local fisheries office.
Sources: Wikipedia (CC BY-SA — summary in our own words, credit only); All Japan Nishikigoi Promotion Association official; Ministry of Agriculture, Forestry and Fisheries (MAFF) and Finance Ministry trade statistics as published; Japanese Agricultural Standard (JAS) for nishikigoi variety names and definitions (2022); Niigata Prefecture, Ojiya City, Nagaoka City (Yamakoshi) and Nishikigoi no Sato official; Japan National Tourism Organization (JNTO) visitor statistics; USDA APHIS and Australian DAFF official import guidance. Checked 6 November 2026.