Black Ghost Knifefish and Cardinal Tetra Compatibility Overview
Black Ghost Knifefish and Cardinal Tetra are generally not recommended to be housed together. The adult size gap creates a meaningful predation risk. Their pH ranges overlap only partly, so aim for the shared band and keep it steady. Review the behavior and water details before deciding whether to attempt the pairing.
| Factor | Black Ghost Knifefish | Cardinal Tetra | Verdict |
|---|---|---|---|
| Temperature | 73โ82ยฐF | 73โ82ยฐF | โ 73โ82ยฐF |
| pH Range | 6.0โ8.0 | 4.5โ7.0 | โ 6.0โ7.0 |
| Temperament | semi | peaceful | โ ๏ธ Monitor |
| Adult Size | 18.0 in | 1.5 in | โ 12ร difference |
| Min. Group | 1+ | 6+ | See below |
| Min. Tank Size | 100 gallons (for both species) | โ | |
Compatibility Positives
Incompatibility Reasons
Species Profiles
Black Ghost Knifefish โ Apteronotus albifrons
The Black Ghost Knifefish is a unique and elegant addition to the aquarium. With a lifespan of 5-8 years, it requires a minimum tank size of 200 liters. It is a solitary fish with a low aggression level and moderate activity. Its slender body and silver-blue coloration make it a captivating sight.
โ Full Black Ghost Knifefish care guide
Cardinal Tetra โ Paracheirodon axelrodi
Brilliant red-and-blue schooling fish from the Rio Negro. Prefers soft, acidic, warm water โ a natural companion for discus.
Frequently Asked Questions
Can Black Ghost Knifefish live with Cardinal Tetra?
Generally not recommended. Black Ghost Knifefish and Cardinal Tetra are generally not recommended to be housed together. The adult size gap creates a meaningful predation risk. Their pH ranges overlap only partly, so aim for the shared band and keep it steady. Review the behavior and water details before deciding whether to attempt the pairing.
What tank size do I need for Black Ghost Knifefish and Cardinal Tetra together?
A minimum of 100 gallons is recommended for keeping Black Ghost Knifefish and Cardinal Tetra together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Black Ghost Knifefish and Cardinal Tetra?
73โ82ยฐF โ inside Black Ghost Knifefish's 73โ82ยฐF and Cardinal Tetra's 73โ82ยฐF.
Is a Black Ghost Knifefish aggressive toward a Cardinal Tetra?
The adult size gap creates a meaningful predation risk.
Related Compatibility Guides
Tank Size for Black Ghost Knifefish and Cardinal Tetra
Use the scenario that matches the actual group sizes and temperament you plan to keep.
| Scenario | Tank | When it applies |
|---|---|---|
| Minimum viable | 100 gal | Only for the recommended minimum groups, mature filtration, and close monitoring. |
| Recommended community | 150 gal | Adds territory, swimming room, and a safer buffer for behavior. |
| Low-conflict setup | 220 gal | Best when keeping larger schools or reducing territorial pressure. |