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Japanese ricefish (medaka)
Natural grey-brown medaka; ornamental colours do not create new species.
A translucent grey-brown ricefish with a silver belly and a long posterior anal fin.
- Adult length
- Up to 3.6 cm (standard length, without the tail fin)
- Water temperature
- 16–22 °C
- Lifespan
- Up to 5 years
- pH
- 6.5–8.5
- Hardness
- 5–25 dGH
- Natural habitat
- Inhabits lowland ponds, marshes, rice fields and slow streams; some populations also occur in brackish water and coastal tide pools.
Needs seasonal, temperate-to-subtropical conditions, not year-round tropical heating. Small sunlit containers can overheat.
Appearance and identification
Adult males usually have extended dorsal and anal fins. Unlike Daisy's ricefish, it lacks the conspicuous blue flank, orange-red belly edge and red tail margins.
Same-species behaviour
Keep eight or more. Allow space for courtship interactions.
Space requirements
At least a 45 × 30 cm base with open swimming room and planted cover.
Diet and feeding
Use suitably small prepared food plus small live or frozen prey; do not rely on food growing in the tank.
Compatibility limits
Match seasonal conditions and adult sizes, exclude predators, and keep ricefish species or uncertain stocks apart when preserving lineages.
Aquarium environment
Fine plants provide cover and egg attachment sites. Adults can eat fry.
Similar and related fish
Sources
www.fishbase.se ↗ 2026-10-25
www.seriouslyfish.com ↗ 2026-10-22
www.aquariumglaser.de ↗ 2026-10-22
journals.plos.org ↗ 2026-10-22