Compatibility Overview
Black Neon Tetra 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 | Black Neon Tetra | Pajama Cardinalfish | Verdict |
|---|---|---|---|
| Temperature | 72–82°F | 72–82°F | ✅ 72–82°F |
| pH Range | 6.0–7.0 | 8.0–8.3 | ❌ No overlap |
| Temperament | semi | semi | ⚠️ Monitor |
| Adult Size | 0.8 in | 1.6 in | ⚠️ 2.0× difference |
| Min. Group | 6+ | 1+ | See below |
| Min. Tank Size | 40 gallons (for both species) | — | |
✅ Compatibility Positives
❌ Incompatibility Reasons
Species Profiles
Black Neon Tetra — Aquarium species
The Black Neon Tetra is a popular freshwater species known for its vibrant colors and peaceful temperament. It is an excellent addition to community tanks, thriving in groups of 6 or more. These tetras require a well-maintained aquarium with a flowing current and plenty of swimming space. With proper care, they can live up to 5 years. They are adaptable to v
→ Full Black Neon Tetra 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 Black Neon Tetra live with Pajama Cardinalfish?
Generally not recommended. Black Neon Tetra 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 Black Neon Tetra and Pajama Cardinalfish together?
A minimum of 40 gallons is recommended for keeping Black Neon Tetra and Pajama Cardinalfish together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Black Neon Tetra and Pajama Cardinalfish?
72–82°F
Is a Black Neon Tetra aggressive toward a Pajama Cardinalfish?
Black Neon Tetra 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 | 72/100 |
| 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 | 40 gal | Only for the recommended minimum groups, mature filtration, and close monitoring. |
| Recommended community | 55 gal | Adds territory, swimming room, and a safer buffer for behavior. |
| Low-conflict setup | 90 gal | Best when keeping larger schools or reducing territorial pressure. |