Harlequin Rasbora (Trigonostigma heteromorpha)

Add a splash of vibrant color and synchronized movement to your aquarium with the Harlequin Rasbora. Famous for the distinctive, black "lamb-chop" wedge on their shimmering copper bodies, these fish are the gold standard for community aquariums. Reliable, hardy, and social, they are the perfect choice for both beginners and seasoned aquascapers.

Quick Care Overview

• Origin: Southeast Asia (Thailand, Malaysia, Singapore, and Sumatra)

• Temperament: Peaceful and Social

• Size: Up to 2 inches (5 cm)

• Minimum Tank Size: 10–15 Gallons

• Water Temperature: 72°F to 82°F

• pH Level: 6.0 – 7.5

Natural Habitat & Environment

In the wild, Harlequin Rasboras inhabit peat swamp forests and slow-moving streams shaded by dense canopy. To replicate this, use a planted aquarium with species like Cryptocoryne or Java Fern. They appreciate a dark substrate and slightly dimmed lighting, which mimics their blackwater origins and makes their orange-red coloration intensify. Because they are active swimmers, ensure there is plenty of open space in the center of the tank for schooling.

Diet & Feeding

These are unfussy eaters that will accept almost any food offered. For the best health and color, provide a balanced diet of:

• High-quality tropical flakes or micro-pellets.

• Frozen foods such as Bloodworms, Brine Shrimp, and Tubifex.

• Live treats like Daphnia to stimulate natural hunting behaviors.

Ideal Tank Mates

The Harlequin Rasbora is a quintessential community fish. They must be kept in schools of 6 or more to feel secure. Great companions include:

• Small Community Fish: Neon Tetras, Cardinal Tetras, and Dwarf Gouramis.

• Bottom Dwellers: Corydoras Catfish and Kuhli Loaches.

• Invertebrates: Amano Shrimp and Nerite Snails.

• Note: Avoid large, predatory fish that may see these small rasboras as a snack.

Breeding the Harlequin Rasbora

Unlike many other rasboras that scatter eggs, Harlequins are leaf-spawners. They prefer to attach their eggs to the underside of broad-leaved plants (like Anubias). To encourage breeding, provide soft, slightly acidic water and condition the pair with live foods. Once the eggs are laid, it is best to remove the parents to ensure the survival of the fry, which will hatch in about 24 hours.

Why Choose the Harlequin Rasbora?

Few fish offer the same level of hardiness and visual impact. Their tight schooling behavior creates a "shoal" effect that brings life to every corner of the tank. If you want a low-stress, high-beauty addition to your freshwater setup, the Harlequin Rasbora is a classic for a reason.

PLEASE READ BEFORE ORDERING

• The photos shown on fish product pages are representations of adult fish and are NOT the actual fish that you will be receiving. 
• Please visit our “Ordering/Shipping fish” page prior to checking out to familiarize yourself with our process.
• We ship fish exclusively using overnight shipping with either FedEx or UPS. We will not ship fish with lesser expensive shipping services like “Ground” or “Priority Mail”. This is to ensure the safety of the fish. 
• Unless specified, all fish are sold as unsexed.