Harlequin rasbora

Trigonostigma heteromorpha

A copper-coloured body with a black triangular patch

The broad black triangular patch on the rear flank is its most memorable feature.

Adult length: Up to 5 cm
Water temperature: 21–28 °C
Lifespan: 5–8 years
pH: 5–7.5
Hardness: 5–12 dGH

Natural habitat: Inhabits slow forest streams and tributaries with dense submerged plants, fallen leaves and wood, sometimes in lightly brown water.

Keep in a group of its own species and leave an uninterrupted area for swimming.

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Appearance and identification

A relatively deep body bears a broad black triangular patch on the rear flank. Compare body shape and the outline of the black patch with slender, narrow-marked relatives.

Same-species behaviour

Keep a group of at least 8–10 of the same species.

Space requirements

Allow a footprint of at least about 60 × 30 cm.

Diet and feeding

Small pellets and small frozen or live foods.

Compatibility limits

Usually suitable for peaceful communities of small fish.

Sources

www.seriouslyfish.com ↗ 2026-10-21

www.aquariumcoop.com ↗ 2026-10-21

singapore.biodiversity.online ↗ 2026-10-22