Trigonostigma heteromorpha
Harlequin Rasbora
Harlequin rasboras are hardy, peaceful shoaling fish that suit new fishkeepers wanting an active, colourful community tank without the fussiness of some tetra species.
CyprinidaeLifespan 5–8 yearsCare complexity 2/5Suitable for beginners
At a glance
- Scientific name
- Trigonostigma heteromorpha
- Family
- Cyprinidae
- Origin
- Slow blackwater streams of Malaysia, Sumatra and Thailand
- Lifespan
- 5–8 years
- Adult size
- 3–4.5 cm
- Weight
- Not typically measured
- Temperament
- Calm, sociable shoaling fish that rarely nips fins
- Activity level
- Moderate; steady mid-water shoaling
- Social needs
- High; needs a shoal of eight or more to display confident, natural behaviour
- Intelligence
- Simple shoaling and feeding-response behaviour
- Noise
- Silent
Housing and environment
- Housing
- Planted aquarium of at least 55 litres with soft, slightly acidic water
- Space requirement
- Horizontal swimming space with dense planting for security
- Temperature
- 22–27°C
- Humidity
- Not applicable, aquatic species
- Exercise
- Provided by tank length and shoal swimming
- Grooming
- Not applicable
Diet and feeding
Small flake and micro-pellet foods with occasional live or frozen daphnia
Behaviour and compatibility
Tight shoaling, distinctive triangular black marking display, egg-laying on the underside of broad leaves
- With children
- Good community fish for supervised feeding and observation
- With other animals
- Compatible with other small peaceful community species and shrimp
- Training difficulty
- Not applicable
Health
- Ich
- Fin rot from poor water quality
- Fungal infections after injury
No individual veterinary treatment is realistic; quarantine new stock and maintain stable water quality
Special care requirements
Soft, slightly acidic water improves colour and long-term health compared with hard tap water