Compatibility Overview
Pajama Cardinalfish and Royal Gramma 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 15-gallon tank is recommended to provide adequate territory and water volume for both species.
| Factor | Pajama Cardinalfish | Royal Gramma | Verdict |
|---|---|---|---|
| Temperature | 72–82°F | 73–81°F | ✅ 73–81°F |
| pH Range | 8.0–8.3 | 8.0–8.5 | ⚠️ 8.0–8.3 (narrow) |
| Temperament | semi | semi | ⚠️ Monitor |
| Adult Size | 1.6 in | 1.6 in | ✅ Similar |
| Min. Group | 1+ | 1+ | See below |
| Min. Tank Size | 15 gallons (for both species) | — | |
✅ Compatibility Positives
⚠️ Caution Points
Species Profiles
Pajama Cardinalfish — Aquarium species
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.
→ Full Pajama Cardinalfish care guide
Royal Gramma — Aquarium species
The Royal Gramma, known for its vibrant blue coloration, is a popular saltwater fish among beginners and experienced aquarists alike. It requires a well-maintained tank with plenty of swimming space and a moderate current. With a peaceful temperament and a relatively easy care routine, the Royal Gramma can be a great addition to a community tank. Its delicat
Frequently Asked Questions
Can Pajama Cardinalfish live with Royal Gramma?
Yes, in a well-planned setup. Pajama Cardinalfish and Royal Gramma 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 15-gallon tank is recommended to provide adequate territory and water volume for both species.
What tank size do I need for Pajama Cardinalfish and Royal Gramma together?
A minimum of 15 gallons is recommended for keeping Pajama Cardinalfish and Royal Gramma together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Pajama Cardinalfish and Royal Gramma?
73–81°F
Is a Pajama Cardinalfish aggressive toward a Royal Gramma?
Pajama Cardinalfish is semi and Royal Gramma is semi. No major aggression issues are expected between these species.
Related Compatibility Guides
Compatibility score breakdown
The overall score is weighted across water chemistry, behavior, adult size, swimming zone, and social needs. A score is a planning aid—not a guarantee for individual fish.
| Factor | Score |
|---|---|
| Temperature | 100/100 |
| Ph | 100/100 |
| Temperament | 62/100 |
| Adult Size | 100/100 |
| Swim Zone | 68/100 |
| Social Needs | 92/100 |
Tank size scenarios
Use the scenario that matches the actual group sizes and temperament you plan to keep.
| Scenario | Tank | When it applies |
|---|---|---|
| Minimum viable | 26 gal | Only for the recommended minimum groups, mature filtration, and close monitoring. |
| Recommended community | 40 gal | Adds territory, swimming room, and a safer buffer for behavior. |
| Low-conflict setup | 55 gal | Best when keeping larger schools or reducing territorial pressure. |