Compatibility Overview
Black Ghost Knifefish and Clown Knifefish can generally share an aquarium with appropriate planning. Both species prefer overlapping temperature and pH ranges, and neither poses a major aggression risk to the other. A minimum 100-gallon tank is recommended to provide adequate territory and water volume for both species.
| Factor | Black Ghost Knifefish | Clown Knifefish | Verdict |
|---|---|---|---|
| Temperature | 72–82°F | 72–82°F | ✅ 72–82°F |
| pH Range | 6.0–7.0 | 6.0–7.0 | ✅ 6.0–7.0 |
| Temperament | semi | semi | ⚠️ Monitor |
| Adult Size | 23.6 in | 7.9 in | ⚠️ 3.0× difference |
| Min. Group | 1+ | 1+ | See below |
| Min. Tank Size | 100 gallons (for both species) | — | |
✅ Compatibility Positives
⚠️ Caution Points
Species Profiles
Black Ghost Knifefish — Aquarium species
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. Keep in mind that it may be sensitive to strong currents and
→ Full Black Ghost Knifefish care guide
Clown Knifefish — Aquarium species
The Clown Knifefish is a unique and visually striking species known for its slender body and distinctive coloration. It is a solitary fish that requires a spacious tank to thrive. With a moderate activity level and low aggression, it can be a suitable addition to a community tank with similarly peaceful species. Regular water changes and a balanced diet are
Frequently Asked Questions
Can Black Ghost Knifefish live with Clown Knifefish?
Yes, in a well-planned setup. Black Ghost Knifefish and Clown Knifefish can generally share an aquarium with appropriate planning. Both species prefer overlapping temperature and pH ranges, and neither poses a major aggression risk to the other. A minimum 100-gallon tank is recommended to provide adequate territory and water volume for both species.
What tank size do I need for Black Ghost Knifefish and Clown Knifefish together?
A minimum of 100 gallons is recommended for keeping Black Ghost Knifefish and Clown Knifefish together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Black Ghost Knifefish and Clown Knifefish?
72–82°F
Is a Black Ghost Knifefish aggressive toward a Clown Knifefish?
Black Ghost Knifefish is semi and Clown Knifefish is semi. No major aggression issues are expected between these species.
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 | 100/100 |
| 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 | 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. |