Cardinal Tetra and Harlequin Rasbora Compatibility Overview
Cardinal Tetra and Harlequin Rasbora can generally share an aquarium with appropriate planning. Both species prefer overlapping temperature and pH ranges. Both species are peaceful, and neither poses a major aggression risk to the other. A minimum 20-gallon tank is recommended to provide adequate territory and water volume for both species.
| Factor | Cardinal Tetra | Harlequin Rasbora | Verdict |
|---|---|---|---|
| Temperature | 73โ82ยฐF | 72โ81ยฐF | โ 73โ81ยฐF |
| pH Range | 4.5โ7.0 | 5.5โ7.5 | โ 5.5โ7.0 |
| Temperament | peaceful | peaceful | โ Compatible |
| Adult Size | 1.5 in | 1.75 in | โ Similar |
| Min. Group | 6+ | 8+ | See below |
| Min. Tank Size | 20 gallons (for both species) | โ | |
Compatibility Positives
Caution Points
Species Profiles
Cardinal Tetra โ Paracheirodon axelrodi
Brilliant red-and-blue schooling fish from the Rio Negro. Prefers soft, acidic, warm water โ a natural companion for discus.
โ Full Cardinal Tetra care guide
Harlequin Rasbora โ Trigonostigma heteromorpha
Active mid-level schooling fish with a distinctive black triangular patch. One of the best all-around community tank fish.
Frequently Asked Questions
Can Cardinal Tetra live with Harlequin Rasbora?
Yes, in a well-planned setup. Cardinal Tetra and Harlequin Rasbora can generally share an aquarium with appropriate planning. Both species prefer overlapping temperature and pH ranges. Both species are peaceful, and neither poses a major aggression risk to the other. A minimum 20-gallon tank is recommended to provide adequate territory and water volume for both species.
What tank size do I need for Cardinal Tetra and Harlequin Rasbora together?
A minimum of 20 gallons is recommended for keeping Cardinal Tetra and Harlequin Rasbora together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Cardinal Tetra and Harlequin Rasbora?
73โ81ยฐF โ inside Cardinal Tetra's 73โ82ยฐF and Harlequin Rasbora's 72โ81ยฐF.
Is a Cardinal Tetra aggressive toward a Harlequin Rasbora?
Cardinal Tetra is peaceful and Harlequin Rasbora is peaceful. No major aggression issues are expected between these species.
Related Compatibility Guides
Tank Size for Cardinal Tetra and Harlequin Rasbora
Use the scenario that matches the actual group sizes and temperament you plan to keep.
| Scenario | Tank | When it applies |
|---|---|---|
| Minimum viable | 20 gal | Only for the recommended minimum groups, mature filtration, and close monitoring. |
| Recommended community | 29 gal | Adds territory, swimming room, and a safer buffer for behavior. |
| Low-conflict setup | 55 gal | Best when keeping larger schools or reducing territorial pressure. |