Description
Harlequin Rasbora – Trigonostigma heteromorpha
Introduction:
The Harlequin Rasbora (Trigonostigma heteromorpha) is a striking and hardy freshwater fish renowned for its distinct black triangular marking and vibrant, orange-pink body. These peaceful fish reach about 1.5 to 2 inches (3.8-5 cm) in size and are ideal for community aquariums. Known for their gentle schooling behavior, Harlequin Rasboras bring movement and a splash of color to planted tanks, making them a favorite among beginners and experienced aquarists alike.
1. Natural Habitat and Behavior
Harlequin Rasboras are native to the slow-moving, heavily vegetated streams and swamps of Southeast Asia, particularly in Thailand, Malaysia, and Singapore. They prefer tannin-stained waters rich in plant life, where they can school and hide among dense vegetation. In aquariums, these social fish exhibit a peaceful demeanor and are most comfortable when kept in groups of 6 or more.
2. Aquarium Setup
A 20-gallon tank or larger is recommended for a group of Harlequin Rasboras. They thrive in a well-planted environment with soft, acidic to neutral water (pH 5.5-7.5) and gentle water movement. Leaf litter or driftwood will help replicate their natural habitat, while fine, dark substrate can enhance their colors. Ideal water temperatures range from 72-80°F (22-27°C). Since these fish are surface to mid-level swimmers, ensure open swimming spaces in the middle and top levels of the tank.
3. Diet and Feeding
Harlequin Rasboras are omnivores and appreciate a varied diet. High-quality micro-pellets and flakes form a good staple, while supplemental feedings of live or frozen foods like brine shrimp, daphnia, and bloodworms help boost their health and coloration. They have small mouths, so provide food that’s appropriately sized, and feed them once or twice daily.
4. Compatibility with Other Fish
These peaceful fish make excellent tank mates for other calm, non-aggressive species. Compatible tank mates include small tetras, corydoras catfish, dwarf gouramis, cherry barbs, and peaceful shrimp species. Avoid housing them with larger or more aggressive fish. Harlequin Rasboras are happiest in groups of 8-10 or more, where they’ll feel secure and display their natural schooling behavior.
5. Common Challenges and Tips
- Schooling Needs: Keeping Harlequin Rasboras in small groups can lead to stress and timid behavior, so a group of 8-10 is recommended to ensure they feel comfortable.
- Sensitivity to Water Quality: Harlequin Rasboras are generally hardy but can be sensitive to drastic changes in water quality. Consistent water changes and a well-maintained filter help keep conditions stable.
- Encouraging Color: A well-rounded diet and dim lighting or tannin-rich water will help bring out their natural colors.
Conclusion
The Harlequin Rasbora (Trigonostigma heteromorpha) is a delightful addition to peaceful community tanks. With their vibrant colors, active schooling behavior, and peaceful nature, these fish create a lively yet tranquil aquarium display. A well-planted tank with stable water conditions will allow them to thrive and show off their best colors.
