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Medaka variety with jet-black body. Darker than Black Diamond lineage, with fins also deeply black being most valued. Appreciated for understated beauty.
Karasu (crow) medaka is a black-type improved variety bred to pursue a deep crow-like blackness across the whole body. Among black strains it pushes darkness furthest, and individuals black to the very tips of the fins are most prized. Standard body type, roughly 3–4 cm. Black coloration is strongly influenced by environment — it fades easily in white containers, so keeping fish in dark containers deepens and stabilizes the black (a protective color response). Hardy across roughly 5–30°C in neutral to slightly alkaline water. Its understated, sober beauty offers a different appeal from brighter varieties and enjoys steady popularity. Peaceful and community-compatible. Selectively breeding the darkest parents maintains the jet-black strain.
Origin
Japan (selectively bred variety)
Lifespan
2-3 years
Size
3-4cm
Temperature
5〜30℃(適温20〜28℃)
Medaka pellets, daphnia
White container highlights blackness. Hard to see in dark containers
Select individuals with black fins for breeding
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: (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.
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Moderate sunlight stabilizes black. Avoid excessive sun
Avoid mixing with other varieties to prevent color mixing
Intermediate. This is an intermediate-level species. Some prior experience and knowledge of environmental management are recommended.
The ideal temperature for Karasu Medaka is 5〜30℃(適温20〜28℃). Avoid sudden temperature changes and maintain a stable environment.
The average lifespan of Karasu Medaka is 2-3 years. With proper care and nutrition, they can live a long and healthy life.
Karasu Medaka typically reaches 3-4cm as an adult. Size may vary depending on care conditions and individual genetics.
Karasu Medaka feeds on: Medaka pellets, daphnia. Aim for a balanced diet with appropriate feeding frequency.
The price of Karasu Medaka varies significantly depending on morph, size, and lineage. Check our market price page for the latest pricing information.
Last updated: July 8, 2026