Angelfish and Black Ghost Knifefish Compatibility Overview
Angelfish and Black Ghost Knifefish are generally not recommended to be housed together. The adult size gap creates a meaningful predation risk. Both are semi, so give them a larger, well-planted tank and watch how they settle in. Review the behavior and water details before deciding whether to attempt the pairing.
| Factor | Angelfish | Black Ghost Knifefish | Verdict |
|---|---|---|---|
| Temperature | 74โ84ยฐF | 73โ82ยฐF | โ 74โ82ยฐF |
| pH Range | 6.0โ7.5 | 6.0โ8.0 | โ 6.0โ7.5 |
| Temperament | semi | semi | โ ๏ธ Monitor |
| Adult Size | 6 in | 18.0 in | โ ๏ธ 3.0ร difference |
| Min. Group | 1+ | 1+ | See below |
| Min. Tank Size | 100 gallons (for both species) | โ | |
Compatibility Positives
Incompatibility Reasons
Species Profiles
Angelfish โ Pterophyllum scalare
Elegant South American cichlids with long flowing fins. Generally peaceful but territorial when breeding and will eat very small fish.
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.
Frequently Asked Questions
Can Angelfish live with Black Ghost Knifefish?
Generally not recommended. Angelfish and Black Ghost Knifefish are generally not recommended to be housed together. The adult size gap creates a meaningful predation risk. Both are semi, so give them a larger, well-planted tank and watch how they settle in. Review the behavior and water details before deciding whether to attempt the pairing.
What tank size do I need for Angelfish and Black Ghost Knifefish together?
A minimum of 100 gallons is recommended for keeping Angelfish and Black Ghost Knifefish together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Angelfish and Black Ghost Knifefish?
74โ82ยฐF โ inside Angelfish's 74โ84ยฐF and Black Ghost Knifefish's 73โ82ยฐF.
Is a Angelfish aggressive toward a Black Ghost Knifefish?
The adult size gap creates a meaningful predation risk.
Related Compatibility Guides
Tank Size for Angelfish and Black Ghost Knifefish
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 | 180 gal | Best when keeping larger schools or reducing territorial pressure. |