Can Boeseman's Rainbowfish live with Cardinal Tetra?
Case-by-case. Watch group sizes, tank size, and feeding zones.
Why Boeseman's Rainbowfish and Cardinal Tetra Don't Make an Easy Pair
They can coexist, but you need to manage the setup carefully. The temperament combination (peaceful+peaceful) can work, but you will need to watch them at feeding time for the first week.
Boeseman's Rainbowfish
Melanotaenia boesemani
| Adult Size: | 4.5" |
| Temperament: | peaceful |
| Min Tank: | 30 gal |
| Temperature: | 75-82°F |
| pH Range: | 7.0-8.0 |
Cardinal Tetra
Paracheirodon axelrodi
| Adult Size: | 1.5" |
| Temperament: | peaceful |
| Min Tank: | 10 gal |
| Temperature: | 73-81°F |
| pH Range: | 5.0-7.0 |
Water Parameter Overlap
| Parameter | Boeseman's Rainbowfish | Cardinal Tetra | Overlap |
|---|---|---|---|
| Temperature | 75-82°F | 73-81°F | 6°F ✓ |
| pH | 7.0-8.0 | 5.0-7.0 | No overlap ✗ |
Compatibility Breakdown
Temperament Match: peaceful + peaceful. Both peaceful → minimal conflict.
⚠️ Size Predation Risk: Boeseman's Rainbowfish (4.5") vs Cardinal Tetra (1.5"). A 3.0" gap — the larger fish will view the smaller fish as food.
Score: 60/100 (GOOD ≥80, CAUTION ≥50, RISKY <50).
🔧 Tank Setup Requirements (for Both)
- Minimum tank: 30 gallons — sized for the larger fish in the pair.
- Temperature: keep it between 75°F and 81°F.
- pH: no shared range. One species will be outside its tolerance regardless of what you set.
- Hiding spots: essential for Boeseman's Rainbowfish — caves, plants, or driftwood to retreat when feeling stressed.
- Water changes: 25% weekly minimum. Two species mean double the bioload.
🔧 Tank Stocking Calculator
Enter tank size to calculate safe stocking levels:
Recommended Equipment
Based on tank size 30+ gallons:
High-quality flake food for rainbowfish
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Accuracy note: This tool uses expert rules + FishBase.org data. Individual fish behavior varies — a peaceful individual Boeseman's Rainbowfish may act differently from its species average. Always observe, quarantine new arrivals for 2-4 weeks, and avoid overcrowding. If a pairing says CAUTION, start with a smaller group and a lid.