Fish profile · Cyprinidae
Harlequin rasbora
Trigonostigma heteromorpha
Harlequin rasbora is a small freshwater fish with a conspicuous black triangular patch on each side. It is a peaceful shoaling aquarium fish. A 2020 taxonomic revision distinguishes it from Trigonostigma truncata, a similar fish from the eastern Malay Peninsula.
Last reviewed 13 October 2026 · 4 sources
- Max length
- 3.8 cm
- IUCN
- LC
- Least Concern
- In Malaysia
- Native
- Family
- Cyprinidae
- order Cypriniformes
Category from the IUCN Red List, via GBIF (CC BY 4.0); it may lag the latest Red List assessment.
How big?
Linear scale · hand 18 cm
Up to 3.8 cm.
Where in Malaysia
32 open-licence records · GBIF
- Recorded (open records)
Recorded in Pahang, Johor, Sarawak, and Terengganu. Based on 32 open-licence records on GBIF. Few records can mean few surveys, not few fish.
How to identify
- Large black triangular wedge on the rear half of the body
- Reddish-orange colour around the head and fins
- Deeper body than several related Trigonostigma species
Habitat
Associated with swamp-forest waters of the Malay Peninsula; closely related species can be confused in regional records.
- Native range
- The Malay Peninsula and parts of Southeast Asia.
Aquarium care
- Minimum tank
- 57 L
- Temperature
- 22.8–25.6°C
- pH
- 6.5–7.2
- Temperament
- Peaceful
- Group size
- 6+
Sources
Last reviewed 13 October 2026