Harlequin Rasbora
Trigonostigma heteromorpha
Harlequin Rasbora (Trigonostigma heteromorpha) — Easy care, Peaceful, under Rasbora. Minimum tank in the app: 14.5 US gal min; aim for 72–82°F and pH 5.5–7.5. The Harlequin Rasbora is perfect for community tanks, appealing to both novice and experienced aquarists due to its vibrant coloration and peaceful nature.

Captive lifespan reflects typical experience in a home aquarium, not maximum recorded age; genetics, sourcing, and care vary.
Natural distribution
Southeast Asia
- East & Southeast Asia
Regional colours match the stocking calculator’s origin map.
Harlequin Rasbora Tank Setup
Create a balanced environment with plenty of plants for cover and open areas for swimming. A substrate that blends with their natural habitat enhances their coloration, while moderate lighting promotes a sense of safety without hindering visibility. Ensure flow is gentle to cater to their mid to upper swimming zone preference.
What Do Harlequin Rasboras Eat?
They exhibit a moderate feeding speed, so provide small, varied foods to prevent competition and encourage natural foraging behavior. Ensure a balanced diet to support their vibrant colors and overall health, avoiding overfeeding which can lead to water quality issues.
Harlequin Rasbora Tank Mates
Opt for similarly sized, peaceful species, such as small tetras or corydoras, to complement the Harlequin Rasbora's temperament. Be cautious of overly aggressive fish or those that occupy the same mid-level swimming space, as this can lead to stress. Maintain groups of at least six to promote social stability and reduce intraspecies aggression.
Are Harlequin Rasboras Good for Beginners?
In App-aquatic we file this under easy care. That still means a cycled tank, realistic stocking, and parameters that do not swing every weekend. Aquarists often underestimate the importance of group size, leading to stress when these fish are kept in small numbers. neglecting water parameters can result in health issues, as they are sensitive to sudden changes in pH and temperature, which can further exacerbate stress.
Building a community? Run the full list through the stocking calculator before you add anything else.
Log tests and reminders in App-aquatic—free, same data you see here.




