Miyuki

Miyuki key facts

Care level

Beginner-friendly

Lifespan

2-3 years

Size

3-4cm

Temperature

5〜30℃（適温20〜28℃）

Diet

Prepared food, daphnia, brine shrimp

Container

Dark containers enhance the metallic sheen

Selection

Breeding high-coverage pairs improves offspring quality

Breeding

Easy like Youkihi. Fry selection is key for quality

Notes

Metallic coverage changes with growth; early grading is unreliable

About Miyuki

Miyuki is one of the most iconic varieties of improved medaka, believed to have been developed in the early 2010s by Yoshiteru Aoki, a specialist in selectively bred medaka from Aichi Prefecture. The name "Miyuki" comes from his son's name, and the variety rapidly became a sensation for its extraordinary beauty. Its defining feature is the "body external light" — a lustrous iridescence produced by reflective iridophore cells running along the dorsal surface, shimmering in silver-white to blue-white hues that shift with the angle of light. Fish are graded by the extent of this light coverage, from partial to strong, super, and finally full-body (Tetsukamen), where the entire body from head to tail glows brilliantly. Full-body specimens are the most prized and command premium prices. In temperament, Miyuki are gentle and sociable, swimming comfortably in groups and mixing well with other varieties. Care requirements are similar to standard medaka, though dark containers and appropriate lighting can dramatically enhance the display of the body light. As a landmark variety that helped spark Japan's improved medaka boom, Miyuki remains beloved by beginners and serious collectors alike.

7 things to know before welcoming a Miyuki

1. 1Check the Light Grade

   The body outer light is graded as weak, strong, or full body (Tetsu Kabuto), with full body being the rarest and most valuable. When purchasing, confirm the extent of the shine through photos or video. The light coverage may expand as the fish matures but rarely shrinks.

2. 2Water Quality and Clarity

   Clear water significantly enhances the visibility of Miyuki's iridescent sheen. Raising them in transparent (clear water) conditions is preferred over green water for best appreciation of their light. Regular water changes help keep ammonia and nitrite levels low.

3. 3Container Color Affects Appearance

   Dark or black containers create high contrast that makes Miyuki's metallic sheen stand out dramatically. White or clear containers can cause the iridescence to blend in and appear less vivid. For display purposes, a black container is the recommended choice.

4. 4Sunlight and Light Development

   Moderate sunlight is thought to support the development of body outer light, making outdoor keeping potentially beneficial for light extension. However, intense summer sun can rapidly raise water temperature, so use shade covers or netting to maintain a comfortable range of approximately 16–28°C.

5. 5Peaceful Temperament and Tank Mates

   Miyuki has a calm temperament and does well with other similarly sized medaka. However, mixing with other varieties risks crossbreeding, which can dilute the body outer light trait in offspring. If maintaining the variety's traits is a priority, single-variety keeping is recommended.

Frequently asked questions about Miyuki

Q.At what age does Miyuki's body light appear?

A.Body light begins to develop gradually during the juvenile stage and is generally assessable by around 2–3 months of age. The extent of light expression can be influenced by growing conditions such as light exposure, water temperature, and nutrition.

Q.Can full-body Miyuki be bred true?

A.

Useful tools for Miyuki care

Learn more about Miyuki in the encyclopedia

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