Cardinal Tetra and Molly Compatibility Overview
Cardinal Tetra and Molly can potentially coexist, but the combination requires careful attention. Their pH ranges do not meet: Cardinal Tetra wants 4.5โ7.0 and Molly wants 7.5โ8.5. A larger tank (minimum 55 gallons), dense planting, and close monitoring are essential.
| Factor | Cardinal Tetra | Molly | Verdict |
|---|---|---|---|
| Temperature | 73โ82ยฐF | 72โ82ยฐF | โ 73โ82ยฐF |
| pH Range | 4.5โ7.0 | 7.5โ8.5 | โ No overlap |
| Temperament | peaceful | peaceful | โ Compatible |
| Adult Size | 1.5 in | 4 in | โ ๏ธ 2.7ร difference |
| Min. Group | 6+ | 3+ | See below |
| Min. Tank Size | 55 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
Molly โ Poecilia sphenops
Hardy livebearers that prefer alkaline, hard water โ sometimes slightly brackish. Prolific breeders; peaceful community fish.
Frequently Asked Questions
Can Cardinal Tetra live with Molly?
With significant caution and a larger tank. Cardinal Tetra and Molly can potentially coexist, but the combination requires careful attention. Their pH ranges do not meet: Cardinal Tetra wants 4.5โ7.0 and Molly wants 7.5โ8.5. A larger tank (minimum 55 gallons), dense planting, and close monitoring are essential.
What tank size do I need for Cardinal Tetra and Molly together?
A minimum of 55 gallons is recommended for keeping Cardinal Tetra and Molly together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Cardinal Tetra and Molly?
73โ82ยฐF โ inside Cardinal Tetra's 73โ82ยฐF and Molly's 72โ82ยฐF.
Is a Cardinal Tetra aggressive toward a Molly?
Cardinal Tetra is peaceful and Molly is peaceful. No major aggression issues are expected between these species.
Related Compatibility Guides
Tank Size for Cardinal Tetra and Molly
Use the scenario that matches the actual group sizes and temperament you plan to keep.
| Scenario | Tank | When it applies |
|---|---|---|
| Minimum viable | 55 gal | Only for the recommended minimum groups, mature filtration, and close monitoring. |
| Recommended community | 75 gal | Adds territory, swimming room, and a safer buffer for behavior. |
| Low-conflict setup | 125 gal | Best when keeping larger schools or reducing territorial pressure. |