Harlequin Rasbora

Trigonostigma heteromorpha has been a staple of the aquarium hobby for nearly a century, valued for its stunning colouration, peaceful nature, and ease of care. Native to slow-moving, heavily vegetated streams and peat swamps across the Thai-Malay Peninsula and Sumatra, it thrives in soft, slightly acidic water with leaf litter and tannins. A school of a dozen or more under warm lighting against a dark substrate is one of the most iconic sights in the planted aquarium hobby.

Water: 22–28 °C, pH 6.0–7.5, soft to moderately hard (GH 4–15). Tank: 60 L minimum; dense planting with open midwater, dark substrate, diffuse lighting. Feeding: Omnivore — accepts quality flakes, micro pellets, Daphnia, and frozen bloodworm. Behaviour: Peaceful schooling fish; keep 8+ for natural behaviour and best colouration. Compatibility: Ideal with other peaceful community fish, dwarf cichlids, corydoras, and shrimp.