Cardinal Tetra and Harlequin Rasbora Compatibility
Cardinal Tetra and Harlequin Rasbora make a good match: temperature ranges overlap at 73–82°F, water chemistry aligns, and neither presents a meaningful behavioural or size risk. Plan on at least 20 gallons. Individual fish vary — observe behaviour during introduction.
Cardinal Tetra vs Harlequin Rasbora at a glance
| Aspect | Cardinal Tetra | Harlequin Rasbora |
|---|---|---|
| Adult size | ~2 in | ~1.8 in |
| Minimum tank | 20 gal | 10 gal |
| Temperature | 73–82°F | 72–82°F |
| pH | 5–7 | 6–7.5 |
| Temperament | peaceful | peaceful |
| Swimming zone | middle | middle |
| Group size | 6+ | 6+ |
| Care level | moderate | easy |
Overlap in temperature: 73–82°F. Overlap in pH: 6–7.
Why this verdict
- Temperature: Shared range of 73–82°F.
- Water parameters: Shared pH range of 6–7.
- Temperament: Both species are peaceful community fish.
- Adult size: Comparable adult sizes (~2" and ~1.8").
- Swimming zone: Both are middle-dwelling, but peaceful — sharing the layer is fine with cover.
- Schooling: Group sizes matter: Cardinal Tetra: keep at least 6; Harlequin Rasbora: keep at least 6.
- Tank size: Plan for at least 20 gallons to satisfy both species.
Main risks
No standout risks — a peaceful pairing that works in a settled community tank.
Recommended tank
Plan on 20 gallons or larger for this pair. Suitable sizes: 20 gallon High, 20 gallon Long, 29 gallon.
Group sizes: Cardinal Tetra: keep at least 6; Harlequin Rasbora: keep at least 6.
Sources
- FishBase — Scientific Database · Primary / scientific · https://www.fishbase.se/
- SeriouslyFish — Specialist Publication · High authority · https://www.seriouslyfish.com/
- Aquarium Forge editorial guidelines — Editorial Interpretation · Editorial interpretation
- FishBase — Scientific Database · Primary / scientific · https://www.fishbase.se/
- SeriouslyFish — Specialist Publication · High authority · https://www.seriouslyfish.com/
- Aquarium Forge editorial guidelines — Editorial Interpretation · Editorial interpretation
- Aquarium Forge editorial guidelines — Editorial Interpretation · Editorial interpretation
Compatibility verdicts are planning guidance, not guarantees — individual fish vary. Rule version 1.1 · Data reviewed: .
Frequently asked questions
Can Cardinal Tetra and Harlequin Rasbora live together?
Our verdict is “Good Match”. Cardinal Tetra and Harlequin Rasbora make a good match: temperature ranges overlap at 73–82°F, water chemistry aligns, and neither presents a meaningful behavioural or size risk. Plan on at least 20 gallons. Individual fish vary — observe behaviour during introduction.
What tank size do Cardinal Tetra and Harlequin Rasbora need?
Plan for at least 20 gallons so both species have their minimum space — Cardinal Tetra needs 20+ gal and Harlequin Rasbora needs 10+ gal. Adding length and cover reduces stress further.
What temperature do Cardinal Tetra and Harlequin Rasbora share?
Their comfortable ranges overlap at 73–82°F. Hold the tank near the middle of that band and avoid the extremes of either species' range.
What are the main risks keeping Cardinal Tetra with Harlequin Rasbora?
There are no standout behavioural or size risks — the usual care and a settled, well-filtered tank is enough.
How many Cardinal Tetra and Harlequin Rasbora should I keep?
Cardinal Tetra: keep at least 6; Harlequin Rasbora: keep at least 6. Group sizes matter for shoaling fish — too few and they become stressed and nippy.
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