Harlequin Rasbora

The Harlequin Rasbora is one of the most popular and elegant freshwater schooling fish, known for its copper-orange body and distinctive black triangular “harlequin” patch on the rear half. Native to Southeast Asia, it is hardy, peaceful, and ideal for planted community aquariums. Its synchronized swimming and vibrant coloration make it a standout choice for both beginners and experienced aquarists.  

Harlequin Rasbora (Trigonostigma heteromorpha) – Complete Care Guide Description The Harlequin Rasbora is one of the most popular and elegant freshwater schooling fish, known for its copper-orange body and distinctive black triangular “harlequin” patch on the rear half. Native to Southeast Asia, it is hardy, peaceful, and ideal for planted community aquariums. Its synchronized swimming and vibrant coloration make it a standout choice for both beginners and experienced aquarists. Water Parameters Stable, slightly soft and mildly acidic water is ideal: Temperature: 23–28°C (73–82°F) pH: 6.0–7.5 Hardness: 2–12 dGH Tank Size: Minimum 60–80 liters (15–20 gallons) Water Flow: Gentle to moderate Water Changes: 20–30% weekly Care & Maintenance Harlequin Rasboras are hardy and easy to care for: Keep in groups of at least 6–10 for natural schooling behavior. Provide a planted aquarium with open swimming space. Maintain stable water conditions and good filtration. Use moderate lighting to enhance their warm coloration. Feed a varied diet: flakes, micro pellets, and live/frozen foods (daphnia, brine shrimp). Avoid strong currents. Behaviour & Temperament Peaceful and active schooling fish. Swim gracefully in mid-water levels. Non-aggressive and ideal for community setups. Can be slightly shy if kept in small groups. Display best color and behavior in larger schools. Compatibility Excellent for peaceful community aquariums. Compatible with a wide range of small, non-aggressive fish. Avoid aggressive or highly territorial species. Suitable Tank Mates Tetras (Neon, Cardinal, Ember) Other rasboras Corydoras catfish Small gouramis Dwarf cichlids (Apistogramma, Rams) Pencilfish Tank Mates to Avoid Aggressive cichlids Large predatory fish Fin-nipping species Very boisterous or hyperactive fish Fish with incompatible water requirements Pro Tips Keep in larger schools for better color and reduced stress. Use dark substrate and plants to enhance coloration. Maintain consistent water quality. Add plants and driftwood to mimic natural habitat. Feed a balanced and varied diet. Use a secure lid—they can jump occasionally. Summary The Harlequin Rasbora is a peaceful, hardy, and visually striking fish that thrives in community aquariums. With proper group size, stable conditions, and compatible tank mates, it adds elegance, color, and synchronized movement to any freshwater setup.