Shusui Koi: The Doitsu Descendant of Asagi

Shusui koi — doitsu scale-line koi with blue and red coloring in a garden pond

Introduction

Shusui is a variety that bridges two worlds — the ancient heritage of Asagi and the sleek, scale-free aesthetic of Doitsu koi. The result is a fish of remarkable visual clarity: a pale blue body, a single row of large mirror scales along the dorsal line, and vivid red or orange markings that seem to glow against the cool base. At Crystal Creek Koi Farm, Shusui is a variety we celebrate for its unique combination of history, elegance, and modern refinement.

History and Origins

Shusui was created in the early 20th century by Yoshigoro Akiyama, who crossed Asagi with Doitsu (German mirror carp). The name "Shusui" means "autumn water" in Japanese — a poetic reference to the cool blue tones of the fish's body, reminiscent of still water in the fall season. Shusui was the first Doitsu variety to be developed in Japan and remains one of the most beloved.

Appearance and Pattern

Shusui's defining characteristics set it apart from all other koi varieties:

  • Doitsu scaling: Unlike fully scaled koi, Shusui has a mostly scale-free body with a single row of large, prominent mirror scales running along the dorsal line (back) and sometimes along the lateral line. These scales should be uniform in size and neatly aligned.
  • Blue body: The base color is a soft, pale blue — similar to Asagi but without the reticulated scale pattern. The blue should be clean and consistent across the body.
  • Hi (red/orange) markings: Vivid red or orange appears on the cheeks, belly, sides, and at the base of the fins. The hi should be bright, well-defined, and symmetrically placed.
  • Head: The head should be pale and clean, free of hi markings. A clear, light-colored head is a quality indicator.

Judging and Quality Standards

Show-quality Shusui are evaluated on:

  • The alignment and uniformity of the dorsal mirror scales
  • The clarity and consistency of the blue body color
  • The brightness and placement of the hi markings
  • The cleanliness of the head
  • Overall body conformation — a deep, well-proportioned body is ideal

Care and Pond Requirements

Shusui share care requirements with other koi varieties and are generally hardy fish:

  • Water quality: Maintain ammonia and nitrite at 0 ppm, nitrate below 20 ppm, and pH between 7.0–8.0.
  • Temperature: Shusui thrive in temperatures between 59–77°F (15–25°C) and are cold-hardy for overwintering.
  • Diet: A high-quality diet with color-enhancing ingredients will help maintain the vibrancy of the hi markings. Feed 2–4 times daily during warmer months.
  • Pond size: A minimum of 1,000 gallons is recommended. Shusui are active swimmers that benefit from ample space.
  • Scale care: The large mirror scales of Doitsu koi can be more susceptible to injury. Ensure pond environments are free of sharp edges or abrasive surfaces.

Color Development Over Time

Like Asagi, Shusui can experience "hi rising" as they age — the red markings gradually spreading up the body. While this is a natural aging process, it is considered a fault in show fish. Young Shusui with well-contained hi and a clean blue body are the most prized for competitive showing.

Why Add Shusui to Your Pond?

Shusui offer a unique aesthetic that no other variety can replicate. The combination of cool blue tones, bold mirror scales, and vivid red accents creates a fish that is simultaneously serene and striking. Their Doitsu scaling gives them a sleek, modern look that contrasts beautifully with fully scaled varieties in a mixed pond.

At Crystal Creek Koi Farm, our Shusui are selected for scale alignment, color clarity, and strong body conformation. Browse our current selection and bring home a piece of koi history.

Shop Live Koi at Crystal Creek

Shusui are a striking blend of Doitsu scaling and Asagi coloration — a true conversation piece for any pond. Browse our current inventory.