Compatibility Overview
Pajama Cardinalfish and Silver Arowana are generally not recommended to be housed together. The issues listed above — whether water parameter incompatibility, predation risk, or aggression — create conditions where one or both fish are likely to suffer harm or chronic stress.
| Factor | Pajama Cardinalfish | Silver Arowana | Verdict |
|---|---|---|---|
| Temperature | 72–82°F | 72–86°F | ✅ 72–82°F |
| pH Range | 8.0–8.3 | 6.0–7.5 | ❌ No overlap |
| Temperament | semi | semi | ⚠️ Monitor |
| Adult Size | 1.6 in | 19.7 in | ❌ 12× difference |
| Min. Group | 1+ | 1+ | See below |
| Min. Tank Size | 100 gallons (for both species) | — | |
✅ Compatibility Positives
❌ Incompatibility Reasons
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
Silver Arowana — Aquarium species
The Silver Arowana is a majestic and unique fish known for its striking appearance and size. It is a large, predatory fish that requires a spacious tank and specific water conditions. While not a community fish, it can be kept with compatible, larger species. They are sensitive to stress and require careful water quality management.
Frequently Asked Questions
Can Pajama Cardinalfish live with Silver Arowana?
Generally not recommended. Pajama Cardinalfish and Silver Arowana are generally not recommended to be housed together. The issues listed above — whether water parameter incompatibility, predation risk, or aggression — create conditions where one or both fish are likely to suffer harm or chronic stress.
What tank size do I need for Pajama Cardinalfish and Silver Arowana together?
A minimum of 100 gallons is recommended for keeping Pajama Cardinalfish and Silver Arowana together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Pajama Cardinalfish and Silver Arowana?
72–82°F
Is a Pajama Cardinalfish aggressive toward a Silver Arowana?
Pajama Cardinalfish is semi and Silver Arowana is semi. These animals require different water types and cannot share one aquarium.
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 | 0/100 |
| Temperament | 62/100 |
| Adult Size | 8/100 |
| 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 | 528 gal | Only for the recommended minimum groups, mature filtration, and close monitoring. |
| Recommended community | 750 gal | Adds territory, swimming room, and a safer buffer for behavior. |
| Low-conflict setup | 950 gal | Best when keeping larger schools or reducing territorial pressure. |