Compatibility Overview
Cardinal Tetra and Molly can generally share an aquarium with appropriate planning. Both species prefer overlapping temperature and pH ranges, and neither poses a major aggression risk to the other. A minimum 55-gallon tank is recommended to provide adequate territory and water volume for both species.
| Factor | Cardinal Tetra | Molly | Verdict |
|---|---|---|---|
| Temperature | 73–82°F | 72–82°F | ✅ 73–82°F |
| pH Range | 4.5–7.0 | 7.5–8.5 | ❌ No overlap |
| Temperament | peaceful | peaceful | ✅ Compatible |
| Adult Size | 1.5 in | 4 in | ⚠️ 2.7× difference |
| Min. Group | 6+ | 3+ | See below |
| Min. Tank Size | 55 gallons (for both species) | — | |
✅ Compatibility Positives
⚠️ Caution Points
Species Profiles
Cardinal Tetra — Paracheirodon axelrodi
Brilliant red-and-blue schooling fish from the Rio Negro. Prefers soft, acidic, warm water — a natural companion for discus.
→ Full Cardinal Tetra care guide
Molly — Poecilia sphenops
Hardy livebearers that prefer alkaline, hard water — sometimes slightly brackish. Prolific breeders; peaceful community fish.
Frequently Asked Questions
Can Cardinal Tetra live with Molly?
Yes, in a well-planned setup. Cardinal Tetra and Molly can generally share an aquarium with appropriate planning. Both species prefer overlapping temperature and pH ranges, and neither poses a major aggression risk to the other. A minimum 55-gallon tank is recommended to provide adequate territory and water volume for both species.
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?
73–82°F
Is a Cardinal Tetra aggressive toward a Molly?
Cardinal Tetra is peaceful and Molly is peaceful. pH ranges barely or do not overlap: Cardinal Tetra prefers 4.5–7.0; Molly prefers 7.5–8.5.