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Oryzias latipes var.
Improved Youkihi with deeper, more intense crimson. The name 'Koutei' reflects its regal red. Color deepens outdoors.
Koutei (Red Emperor) medaka is a further improved variant of Youkihi featuring an even deeper and more intense crimson-vermilion coloration. The name evokes the overwhelming red presence of an emperor. Multi-generation selective breeding produces lines with particularly excellent coloration approaching true 'deep crimson.' Outdoor sunlight deepens color further; astaxanthin- and carotenoid-rich color-enhancing food maintains and strengthens coloration. Hardy in 5–30°C, neutral to slightly alkaline water. Dark containers and outdoor lotus pots best showcase the deep crimson. Breeding is as easy as Youkihi, with color-quality improvement through selective pairing.
Origin
Japan (selectively bred variety)
Lifespan
1-3 years
Size
3-4cm
Temperature
5〜30℃
Medaka pellets, daphnia
Dark containers make deep red stand out
Sunlight deepens coloration
5-30°C (can overwinter outdoors)
Sources: FishBase: Oryzias latipes / Seriously Fish: Oryzias latipes
改良メダカは体型×体色×柄×光(体内/体外)×鱗(透明鱗)×ラメ×ヒレ等のトレイト合成。掲載は当該品種を構成する確証トレイトのみで遺伝形式は確証のみ付与(不確実は省略)。遺伝形式は交配の参考。
Sources: JMA日本メダカ協会 改良メダカ品種分類マニュアル / 改良メダカWEB図鑑(medakazukan)
A curated selection of notable morphs. Inheritance modes are a breeding-planning guide; actual appearance varies with combos.
Edited & verified by: br-choku editorial team
The taxonomic, regulatory, and husbandry data on this page are compiled and verified against the authoritative primary sources below.
Accepted name: Oryzias latipes var. (Temminck & Schlegel, 1846)
Synonyms: Aplocheilus latipes (Temminck & Schlegel, 1846), Poecilia latipes Temminck & Schlegel, 1846, Oryzias latipes latipes (Temminck & Schlegel, 1846)
Authority databases: FishBase · GBIF · 日本メダカ協会 品種分類マニュアル
Nomenclature follows global taxonomic authority databases.
Find listings for this species
Select and breed deepest-colored individuals
Red color-enhancing feed is effective
Intermediate. This is an intermediate-level species. Some prior experience and knowledge of environmental management are recommended.
The ideal temperature for Koutei Medaka is 5〜30℃. Avoid sudden temperature changes and maintain a stable environment.
The average lifespan of Koutei Medaka is 1-3 years. With proper care and nutrition, they can live a long and healthy life.
Koutei Medaka typically reaches 3-4cm as an adult. Size may vary depending on care conditions and individual genetics.
Koutei Medaka feeds on: Medaka pellets, daphnia. Aim for a balanced diet with appropriate feeding frequency.
The price of Koutei Medaka varies significantly depending on morph, size, and lineage. Check our market price page for the latest pricing information.
Last updated: July 8, 2026