Cardinal Tetra and Discus Compatibility Overview
Cardinal Tetra and Discus can generally share an aquarium with appropriate planning. Both species prefer overlapping temperature and pH ranges. Cardinal Tetra is peaceful and Discus is semi, so give them room and cover rather than assuming they will ignore each other. A minimum 100-gallon tank is recommended to provide adequate territory and water volume for both species.
| Factor | Cardinal Tetra | Discus | Verdict |
|---|---|---|---|
| Temperature | 73โ82ยฐF | 82โ88ยฐF | โ ๏ธ 82โ82ยฐF (narrow) |
| pH Range | 4.5โ7.0 | 5.0โ7.0 | โ 5.0โ7.0 |
| Temperament | peaceful | semi | โ ๏ธ Monitor |
| Adult Size | 1.5 in | 8 in | โ 5ร difference |
| Min. Group | 6+ | 5+ | See below |
| Min. Tank Size | 100 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
Discus โ Symphysodon spp.
The 'king of the aquarium' โ beautiful but demanding. Requires very warm, soft, acidic water that excludes most community fish.
Frequently Asked Questions
Can Cardinal Tetra live with Discus?
Yes, in a well-planned setup. Cardinal Tetra and Discus can generally share an aquarium with appropriate planning. Both species prefer overlapping temperature and pH ranges. Cardinal Tetra is peaceful and Discus is semi, so give them room and cover rather than assuming they will ignore each other. A minimum 100-gallon tank is recommended to provide adequate territory and water volume for both species.
What tank size do I need for Cardinal Tetra and Discus together?
A minimum of 100 gallons is recommended for keeping Cardinal Tetra and Discus together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Cardinal Tetra and Discus?
82โ82ยฐF (narrow) โ inside Cardinal Tetra's 73โ82ยฐF and Discus's 82โ88ยฐF.
Is a Cardinal Tetra aggressive toward a Discus?
The adult size gap creates a meaningful predation risk.
Related Compatibility Guides
Tank Size for Cardinal Tetra and Discus
Use the scenario that matches the actual group sizes and temperament you plan to keep.
| Scenario | Tank | When it applies |
|---|---|---|
| Minimum viable | 100 gal | Only for the recommended minimum groups, mature filtration, and close monitoring. |
| Recommended community | 150 gal | Adds territory, swimming room, and a safer buffer for behavior. |
| Low-conflict setup | 220 gal | Best when keeping larger schools or reducing territorial pressure. |