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The Harlequin Rasbora (Trigonostigma heteromorpha) is a jewel of the community aquarium, renowned for its distinctive appearance and peaceful temperament. Growing to an average size of 1.5 to 2 inches (4-5 cm), these small, schooling cyprinids are instantly recognizable by their striking, wedge-shaped black patch, often described as a 'harlequin mask,' set against a shimmering coppery-orange to pinkish body. Their fins are typically clear or subtly tinted. Harlequin Rasboras are active yet docile, making them ideal inhabitants for a well-maintained tropical tank. They thrive in groups of six or more, displaying their natural schooling behavior and vibrant colors more intensely when in larger numbers. For optimal health and coloration, a tank of at least 10-20 gallons is recommended for a small school, providing ample swimming space amidst dense planting, especially stem plants, and shaded areas created by driftwood or floating vegetation. They prefer soft, slightly acidic water (pH 6.0-7.0) with temperatures between 72-78°F (22-26°C). As omnivores, their diet should consist of a high-quality flake or micro-pellet food, supplemented with frozen or live offerings like brine shrimp, daphnia, or bloodworms to ensure a balanced nutritional intake. Harlequin Rasboras are an excellent choice for a peaceful community aquarium, coexisting harmoniously with other small, non-aggressive fish such as tetras, corydoras, dwarf gouramis, and other rasboras.