Compatibility Overview
Black Ghost Knifefish and Foxface Rabbitfish 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 | Black Ghost Knifefish | Foxface Rabbitfish | Verdict |
|---|---|---|---|
| Temperature | 72–82°F | 73–81°F | ✅ 73–81°F |
| pH Range | 6.0–7.0 | 8.0–8.3 | ❌ No overlap |
| Temperament | semi | semi | ⚠️ Monitor |
| Adult Size | 23.6 in | 3.9 in | ❌ 6× difference |
| Min. Group | 1+ | 1+ | See below |
| Min. Tank Size | 100 gallons (for both species) | — | |
✅ Compatibility Positives
❌ Incompatibility Reasons
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
Foxface Rabbitfish — Aquarium species
The Foxface Rabbitfish is a vibrant and peaceful addition to the marine aquarium. With its striking yellow coloration and dark spots, it adds a splash of color to the tank. They are known for their gregarious nature and can be kept in groups of 2-3. This species is suitable for beginners and intermediate aquarists.
Frequently Asked Questions
Can Black Ghost Knifefish live with Foxface Rabbitfish?
Generally not recommended. Black Ghost Knifefish and Foxface Rabbitfish 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 Black Ghost Knifefish and Foxface Rabbitfish together?
A minimum of 100 gallons is recommended for keeping Black Ghost Knifefish and Foxface Rabbitfish together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Black Ghost Knifefish and Foxface Rabbitfish?
73–81°F
Is a Black Ghost Knifefish aggressive toward a Foxface Rabbitfish?
Black Ghost Knifefish is semi and Foxface Rabbitfish is semi. These animals require different water types and cannot share one aquarium.
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 | 0/100 |
| Temperament | 62/100 |
| Adult Size | 8/100 |
| 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. |