Compatibility Overview
Denison Barb and Pajama Cardinalfish 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 | Denison Barb | Pajama Cardinalfish | Verdict |
|---|---|---|---|
| Temperature | 72–82°F | 72–82°F | ✅ 72–82°F |
| pH Range | 6.0–7.5 | 8.0–8.3 | ❌ No overlap |
| Temperament | semi | semi | ⚠️ Monitor |
| Adult Size | 5.9 in | 1.6 in | ⚠️ 3.7× difference |
| Min. Group | 1+ | 1+ | See below |
| Min. Tank Size | 55 gallons (for both species) | — | |
✅ Compatibility Positives
❌ Incompatibility Reasons
Species Profiles
Denison Barb — Aquarium species
The Denison Barb is a popular freshwater fish known for its vibrant coloration and peaceful nature. It is well-suited for community tanks with other peaceful species. These fish are relatively easy to care for and can thrive in a well-maintained aquarium. They require a spacious tank and should be kept in groups to prevent stress. Regular water changes and a
→ Full Denison Barb care guide
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.
Frequently Asked Questions
Can Denison Barb live with Pajama Cardinalfish?
Generally not recommended. Denison Barb and Pajama Cardinalfish 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 Denison Barb and Pajama Cardinalfish together?
A minimum of 55 gallons is recommended for keeping Denison Barb and Pajama Cardinalfish together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Denison Barb and Pajama Cardinalfish?
72–82°F
Is a Denison Barb aggressive toward a Pajama Cardinalfish?
Denison Barb is semi and Pajama Cardinalfish 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 | 38/100 |
| 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 | 55 gal | Only for the recommended minimum groups, mature filtration, and close monitoring. |
| Recommended community | 75 gal | Adds territory, swimming room, and a safer buffer for behavior. |
| Low-conflict setup | 100 gal | Best when keeping larger schools or reducing territorial pressure. |