Compatibility Overview
Cardinal Tetra and Denison Barb 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 | Cardinal Tetra | Denison Barb | Verdict |
|---|---|---|---|
| Temperature | 73–82°F | 72–82°F | ✅ 73–82°F |
| pH Range | 4.5–7.0 | 6.0–7.5 | ✅ 6.0–7.0 |
| Temperament | peaceful | semi | ⚠️ Monitor |
| Adult Size | 1.5 in | 5.9 in | ⚠️ 3.9× difference |
| Min. Group | 6+ | 1+ | See below |
| Min. Tank Size | 75 gallons (for both species) | — | |
✅ Compatibility Positives
❌ Incompatibility Reasons
Species Profiles
Cardinal Tetra — Paracheirodon axelrodi
Brilliant red-and-blue schooling fish from the Rio Negro. Prefers soft, acidic, warm water — a natural companion for discus.
→ Full Cardinal Tetra care guide
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
Frequently Asked Questions
Can Cardinal Tetra live with Denison Barb?
Generally not recommended. Cardinal Tetra and Denison Barb 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 Cardinal Tetra and Denison Barb together?
A minimum of 75 gallons is recommended for keeping Cardinal Tetra and Denison Barb together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Cardinal Tetra and Denison Barb?
73–82°F
Is a Cardinal Tetra aggressive toward a Denison Barb?
Cardinal Tetra is peaceful and Denison Barb is semi. The adult size gap creates a meaningful predation risk.
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 | 67/100 |
| Temperament | 75/100 |
| 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 | 75 gal | Only for the recommended minimum groups, mature filtration, and close monitoring. |
| Recommended community | 125 gal | Adds territory, swimming room, and a safer buffer for behavior. |
| Low-conflict setup | 150 gal | Best when keeping larger schools or reducing territorial pressure. |