Marbled Sulawesi Medaka

Oryzias marmoratus is endemic to Lake Poso in central Sulawesi, one of the world's oldest and most biodiverse lake systems. The species' distinctive marbled brown-and-cream body patterning is unique among Oryzias and makes it instantly recognisable. Like all Poso lake endemics, it requires warm, moderately hard, alkaline conditions.

Lake Poso has faced significant ecological pressures from invasive flowerhorn cichlids released by local hobbyists, causing population crashes in several endemic fish species. O. marmoratus is considered Vulnerable, and captive populations maintained by dedicated aquarists are important for conservation.

This species is rarely available commercially and is most accessible through specialist Sulawesi fish networks. Care is similar to other Sulawesi Oryzias, requiring warm hard alkaline water. Breeding, while achievable, requires stable, correctly parameterised water to succeed.

Water: 26-30°C, pH 7.5-8.5, moderately hard (GH 8-15) — Lake Poso chemistry required. Tank: 40 L species tank with alkaline substrate and some planting; no competitors. Feeding: high-quality micro granules, baby brine shrimp, and small daphnia. Breeding: egg scatterer; deposit eggs on fine plants or mops; fry easy to raise on microfoods. Compatibility: species-only or Sulawesi Poso biotope with other lake endemics.