Harlequin Rasbora – Trigonostigma heteromorpha – 2 to 2.5 cm

Trigonostigma heteromorpha – Harlequin Rasbora

The Harlequin Rasbora (Trigonostigma heteromorpha) is a small South-East Asian fish and a long-established favourite in the aquarium hobby. Its pink to copper body contrasts beautifully with the distinctive large dark triangular marking on the rear half of each side.

The specimens offered here are approximately 2 to 2.5 cm.

Adult Size

The Harlequin Rasbora generally reaches approximately 4 to 5 cm as an adult.

Water Parameters

Temperature: 22 to 28 °C
pH: 6 to 7.5
Hardness: soft to moderately hard water
Nitrite: 0 mg/L

Nitrite should remain undetectable. Clean, stable and properly filtered water helps keep these fish in good condition.

What Size Aquarium for Harlequin Rasboras?

An aquarium at least 60 cm long provides a suitable basis for keeping a shoal of Harlequin Rasboras.

Plenty of vegetation provides sheltered areas, while part of the aquarium should remain open to give the shoal sufficient swimming space.

Behaviour and Shoaling

Trigonostigma heteromorpha is a peaceful and social species. It is preferable to keep at least 8 to 10 individuals. A larger shoal is even better when aquarium size allows.

Keeping these fish in a shoal encourages natural behaviour and helps them feel more secure in their environment.

The Harlequin Rasbora can live alongside many other peaceful species with compatible aquarium requirements.

Feeding

In the wild, the Harlequin Rasbora feeds on small invertebrates, insects, larvae and other small organisms.

In the aquarium, it readily accepts flakes and small pellets suitable for the size of its mouth. Small frozen or live foods can also be offered as part of a varied diet.

A varied diet helps maintain good condition and attractive colouration.

Breeding

The Harlequin Rasbora is an egg-laying species. Unlike many small cyprinids that simply scatter their eggs, females generally attach their adhesive eggs to the underside of plant leaves.

The adults provide no parental care and may eat the eggs.

Origin

Trigonostigma heteromorpha originates from South-East Asia, where it inhabits mainly calm or slow-moving waters, often amongst abundant vegetation.

Lifespan

The Harlequin Rasbora can live for approximately 5 to 6 years in an aquarium when kept under suitable conditions.

Never Release Aquarium Fish into the Wild

Trigonostigma heteromorpha must never be released into a river, pond, lake or any other natural environment.