Harlequin Rasboras ~ Trigonostigma heteromorpha

The Harlequin Rasbora is a small, peaceful fish known for its striking black triangular patch and shimmering orange-pink body. Native to Southeast Asia, particularly Malaysia, Thailand, and Singapore, this hardy species is a favorite in community aquariums due to its vibrant colors and active schooling behavior. Harlequin Rasboras are easy to care for and ideal for both beginners and experienced aquarists.

- Size: 1.5-2 inches  
- Lifespan: 5-8 years  
- Temperament: Peaceful, social  
- Group/Solitary: Best kept in groups of 6+  
- Food: Omnivorous, flake food, micro-pellets, live/frozen foods (daphnia, brine shrimp)  
- Water Requirements: 72-78°F, pH 6.0-7.5, soft to moderately hard water

Harlequin Rasboras are schooling fish that should be kept in groups of at least six, as they feel secure and show their best colors in larger numbers. They thrive in a well-planted aquarium with open swimming space, where their colors stand out against green plants. A soft substrate, gentle water flow, and slightly acidic water closely mimic their natural habitat. Their diet should consist of high-quality flakes or micro-pellets, supplemented with live or frozen foods like brine shrimp and daphnia to maintain health and vibrant color. Harlequins are very peaceful and compatible with a wide range of tankmates, making them ideal for community tanks.

In the wild, Harlequin Rasboras are found in slow-moving, heavily shaded streams and swamps where they feed on small invertebrates and plant matter. They are adapted to low light and soft, slightly acidic water conditions, so they’ll appreciate the addition of driftwood and leaf litter to simulate their native environment.

Fun Fact: The term "harlequin" traditionally refers to a character in European theater known for wearing a colorful, contrasting costume with distinctive patterns. The bold, triangular marking on the Harlequin Rasbora’s body resembles the playful, dramatic patterns on a harlequin’s outfit, making this unique marking as eye-catching as the fish itself.