Discus and Pajama Cardinalfish Compatibility Overview
Discus and Pajama Cardinalfish are generally not recommended to be housed together. One of these is a marine species and the other is not; they cannot share one aquarium. Their ranges meet only at 82โ82ยฐF, which leaves no margin for a heater drifting or a warm room. Review the behavior and water details before deciding whether to attempt the pairing.
| Factor | Discus | Pajama Cardinalfish | Verdict |
|---|---|---|---|
| Temperature | 82โ88ยฐF | 72โ82ยฐF | โ ๏ธ 82โ82ยฐF (narrow) |
| pH Range | 5.0โ7.0 | 8.1โ8.4 | โ No overlap |
| Temperament | semi | peaceful | โ ๏ธ Monitor |
| Adult Size | 8 in | 3.5 in | โ ๏ธ 2.3ร difference |
| Min. Group | 5+ | 3+ | See below |
| Min. Tank Size | 100 gallons (for both species) | โ | |
Compatibility Positives
Incompatibility Reasons
Species Profiles
Discus โ Symphysodon spp.
The 'king of the aquarium' โ beautiful but demanding. Requires very warm, soft, acidic water that excludes most community fish.
Pajama Cardinalfish โ Sphaeramia nematoptera
The Pajama Cardinalfish is a popular, beginner-friendly fish that can add a splash of color to your aquarium. They are generally peaceful and can be kept in a community tank. With moderate activity levels and a preference for undisturbed swimming spaces, they require a well-maintained water quality and a spacious tank.
Frequently Asked Questions
Can Discus live with Pajama Cardinalfish?
Generally not recommended. Discus and Pajama Cardinalfish are generally not recommended to be housed together. One of these is a marine species and the other is not; they cannot share one aquarium. Their ranges meet only at 82โ82ยฐF, which leaves no margin for a heater drifting or a warm room. Review the behavior and water details before deciding whether to attempt the pairing.
What tank size do I need for Discus and Pajama Cardinalfish together?
A minimum of 100 gallons is recommended for keeping Discus and Pajama Cardinalfish together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Discus and Pajama Cardinalfish?
82โ82ยฐF (narrow) โ inside Discus's 82โ88ยฐF and Pajama Cardinalfish's 72โ82ยฐF.
Is a Discus aggressive toward a Pajama Cardinalfish?
Discus is semi and Pajama Cardinalfish is peaceful. No major aggression issues are expected between these species.
Related Compatibility Guides
Tank Size for Discus and Pajama Cardinalfish
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. |