Javanese Ricefish
Javanese Ricefish
Javanese Ricefish (Oryzias javanicus) is the standard wild-type form — a pale olive-silver body with subtle iridescent scaling and the characteristic upturned mouth and flat-backed profile of the Oryzias genus. The Javanese Ricefish is a distinct species from the Japanese Medaka — a Southeast Asian member of the same genus with a more tropical distribution and slightly different care requirements.
Feeding & Care Tip: Hikari Micro Pellets (crushed or soaked briefly) and Sera Vipan Baby make excellent daily staples — the small particle size suits medaka's small upturned mouth. Supplement 2–3× per week with Hikari Frozen or Freeze-Dried Baby Brine Shrimp and Hikari Frozen Daphnia. Medaka are surface-oriented feeders — floating or slow-sinking foods work best. Feed small amounts 2–3 times daily.
Native to rivers, estuaries, and coastal streams of Java, Sumatra, and surrounding Southeast Asian islands — a more tropical and slightly brackish-tolerant species than the Japanese Medaka. Oryzias javanicus is a distinct species from O. latipes, hardier at warmer temperatures and adaptable to a wider salinity range from fresh to slightly brackish water.
Keep in groups of at least six. Peaceful with all small, peaceful community species. More warmth-tolerant than Japanese Medaka — does not share the cold-water hardiness of O. latipes. Adapts well to hard, slightly alkaline freshwater.
Medaka are egg-scatterers that breed readily with minimal encouragement. Females carry fertilized eggs attached to their belly for a short period before depositing them on plants or a spawning mop. Eggs hatch in 7–14 days depending on temperature. Fry are tiny but immediately free-swimming and can take crushed fine food from day one. In a planted outdoor tub, multiple generations can coexist through the season.
Care & Ideal Parameters
| Difficulty | Easy |
| Temperament | Peaceful — active schooling |
| Typical Adult Size | 1.5 inches (3.8 cm) |
| Min. Group Size | 6 minimum |
| Ideal Temp | 72–82°F (22–28°C) |
| Ideal pH | 7.0–8.5 |
| Ideal GH | 5–20 dGH |
| Ideal KH | 2–12 dKH |
| Staple Food | Hikari Micro Pellets (crushed/soaked); Sera Vipan Baby |
| Treat / Supplement | Hikari Frozen or Freeze-Dried Baby Brine Shrimp; Hikari Frozen Daphnia |
| Origin | Java, Sumatra, and surrounding Southeast Asian islands |
| Notes | Standard wild-type Oryzias javanicus. Distinct from O. latipes — warmer water, brackish tolerant. |
