Can Cardinal Tetra live with Harlequin Rasbora?
These two species are usually compatible in community tanks.
Why Cardinal Tetra and Harlequin Rasbora Work
These two species overlap in both temperature (73–79°F overlap) and pH (5.5-7.0 overlap range). Their temperature tolerances are close enough, and neither fish pushes the pH so far outside the other's comfort zone that it creates chronic stress. The temperament match (peaceful + peaceful) is low-conflict. In a 10+ gallon tank with adequate hiding spots, these two can coexist with minimal problems.
Cardinal Tetra
Paracheirodon axelrodi
| Adult Size: | 1.5" |
| Temperament: | peaceful |
| Min Tank: | 10 gal |
| Temperature: | 73-81°F |
| pH Range: | 5.0-7.0 |
Harlequin Rasbora
Trigonostigma heteromorpha
| Adult Size: | 2.0" |
| Temperament: | peaceful |
| Min Tank: | 10 gal |
| Temperature: | 73-79°F |
| pH Range: | 5.5-7.0 |
Water Parameter Overlap
| Parameter | Cardinal Tetra | Harlequin Rasbora | Overlap |
|---|---|---|---|
| Temperature | 73-81°F | 73-79°F | 6°F ✓ |
| pH | 5.0-7.0 | 5.5-7.0 | 1.5 ✓ |
Compatibility Breakdown
Temperament Match: peaceful + peaceful. Both peaceful → minimal conflict.
Score: 120.0/100 (GOOD ≥80, CAUTION ≥50, RISKY <50).
🔧 Tank Setup Requirements (for Both)
- Minimum tank: 10 gallons — sized for the larger fish in the pair.
- Temperature: keep it between 73°F and 79°F.
- pH: maintain 5.5 – 7.0.
- Hiding spots: essential for Cardinal Tetra — caves, plants, or driftwood to retreat when feeling stressed.
- Water changes: 25% weekly minimum. Two species mean double the bioload.
🔧 Tank Stocking Calculator
Enter tank size to calculate safe stocking levels:
Recommended Equipment
Based on tank size 10+ gallons:
Small floating pellets perfect for tetras
Explore Related Checks
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Accuracy note: This tool uses expert rules + FishBase.org data. Individual fish behavior varies — a peaceful individual Cardinal Tetra may act differently from its species average. Always observe, quarantine new arrivals for 2-4 weeks, and avoid overcrowding. If a pairing says CAUTION, start with a smaller group and a lid.