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Ranchu Medaka
AdvancedNamed for resemblance to Ranchu goldfish — no dorsal fin and round body. A Daruma subtype with uniquely charming form. Poor swimmer, so careful tank mate selection.
Difficulty
Advanced
Temperature
15〜30℃
Lifespan
1-2 years
Size
2-3cm
Diet
Fine medaka pellets, brine shrimp
About
Ranchu medaka is named for its dorsal-fin-less, plump rounded body resembling the ranchu goldfish. Built on the daruma body type (short tail and trunk) with traits such as a missing dorsal fin, its distinctive, endearing form is the appeal. Small at 2–3 cm. Because the body is heavily modified, it swims somewhat poorly and slowly, so it should not be kept with strong, active swimmers but rather with equally gentle, low-mobility varieties. Being less hardy than the standard type and somewhat harder to breed, it is considered a more advanced variety, favored by hobbyists who enjoy attentive care of its unique shape.
Lifespan of the Ranchu Medaka
The Ranchu Medaka lives 1-2 years.
Size of the Ranchu Medaka
The Ranchu Medaka grows to 2-3cm.
Temperature & humidity for the Ranchu Medaka
The ideal temperature for the Ranchu Medaka is 25〜28℃.
It tends to be sensitive to sudden temperature changes and cold, so keeping it in conditions that hold the optimal range (around 25–28°C) — possibly with a heater — is reassuring.
Basic Info
Origin
Japan (selectively bred variety)
Lifespan
1-2 years
Size
2-3cm
Care Specifications
- pH
- 7–8
- Hardness (GH)
- 9–19 dGH
- Water Temp.
- 25–28℃
PeacefulGroupBreeding: Easy
Sources: FishBase: Oryzias latipes / Seriously Fish: Oryzias latipes
Morphs (Varieties)
Selectively bred killifish are trait combinations of body form × body color × pattern × luminescence (internal/external) × scale types (transparent scales) × sparkle × fin morphology and so forth. Published entries include only confirmed traits constituting the given variety, with genetic inheritance patterns provided only for confirmed traits (uncertain cases omitted). Genetic patterns are provided as reference for breeding.
RecessiveVisual only with two copies; one copy = het (carrier).
Daruma (short body)
Sources: JMA Japan Medaka Association — Improved Medaka Variety Classification Manual (JA) / Improved Medaka Web Encyclopedia (medakazukan, JA)
A curated selection of notable morphs. Inheritance modes are a breeding-planning guide; actual appearance varies with combos.
References & Sources
Edited & verified by: BreederDirect editorial team
The taxonomic, regulatory, and husbandry data on this page are compiled and verified against the authoritative primary sources below.
Taxonomy & Authority
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 · Japan Medaka Association — Variety Classification Manual (JA)
Nomenclature follows global taxonomic authority databases.
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