Can African Knifefish and Finger Fish Live Together?

Not Recommended

African Knifefish and Finger Fish are not recommended as tank mates due to incompatible water types. Housing these species together is likely to result in stress, health problems, or direct harm to one or both fish.


At a Glance

African Knifefish

Xenomystus nigri

Finger Fish

Monodactylus argenteus

🐟Family Group
African Knifefish
Oddballs
Finger Fish
Oddballs
Temperament
African Knifefish
Semi-Aggressive (5/10)
Finger Fish
Semi-Aggressive (5/10)
Temperature
✓ Compatible
African Knifefish
23–28°C
Finger Fish
24–28°C
pH Range
✓ Compatible
African Knifefish
6–7.5
Finger Fish
7.5–8.5
Hardness (dGH)
✓ Compatible
African Knifefish
2–15
Finger Fish
12–30
Water Type
✗ No overlap
African Knifefish
Freshwater Only
Finger Fish
Brackish Required
Flow Preference
✓ Compatible
African Knifefish
Low
Finger Fish
Moderate
Min Tank Volume
Combined: 470 L
African Knifefish
200 L
Finger Fish
470 L
Swimming Level
Shared: 1 zone
African Knifefish
MiddleBottom
Finger Fish
Middle
🏷️Behavior Tags
African Knifefish
Piscivore (Eats small/nano fish)Shrimp EaterNocturnalShy / Slow Moving (Easily Stressed)Aggressive to same species/look-alikes
Finger Fish
Hyperactive / Fast SwimmerFin NipperPlant DestroyerAggressive to same species/look-alikes
Stocking calculator

Can your tank handle African Knifefish and Finger Fish?

Compatibility is only part of the answer. Test both fish with your real tank size, current stock, and maintenance needs to see if you have enough space and a safe stocking level before you add them.

African Knifefish
Finger Fish
Test both in my tank

Behaviour & Temperament

Both African Knifefish and Finger Fish are moderately assertive species with an aggression score of 5/10. Their matching temperaments mean neither fish is likely to dominate the other in a shared aquarium.

African Knifefish and Finger Fish both frequent the Middle (Open Water) region of the setup. This overlap can increase competition for space, so providing ample room and cover is important to keep both species comfortable.

Additional behavioural considerations to keep in mind: Hyperactive swimmers can stress shy, slow-moving species through constant motion.

Worth noting: African Knifefish is nocturnal and will be most active after lights-out, naturally reducing daytime encounters.

Water Parameters

The safe temperature window for both species falls between 24°C and 28°C. Aim for the midpoint of this range (around 26.0°C) for optimal comfort.

Both fish can tolerate a pH between 7.5 and 7.5. Maintaining a stable value within this band is more important than hitting an exact number.

For general hardness, the shared comfort zone is 12–15 dGH. Regular testing will ensure conditions stay within this range.

Crucially, these species require different water types — one needs freshwater while the other requires brackish conditions. This is a hard barrier to keeping them together.

Tank Setup

To house African Knifefish and Finger Fish together, plan for an aquarium of at least 470 litres with a minimum length of 150 cm. This recommendation combines the stricter species minimums with a community-load allowance so the pairing has realistic long-term space and filtration headroom.

Providing a mix of open swimming space and sheltered areas with rocks, driftwood, or plants will keep both species comfortable and allow natural behaviour.

Specific environmental needs for this combination include: Driftwood (Digestion/Hiding), Smooth Gravel (Sensitive Barbels), Plants - Floating. Meeting these requirements will help both species thrive.

Both species do well with low (still water) water movement, so a standard filtration setup rated for the tank volume should suffice.

Suitable Tank Sizes

Standard aquarium sizes large enough for both African Knifefish and Finger Fish.

Frequently Asked Questions

Can African Knifefish and Finger Fish live together?

No. This combination is not recommended. Key incompatibilities — such as different water type needs — make cohabitation unsafe.

What size tank do African Knifefish and Finger Fish need?

A minimum of 470 litres (tank length at least 150 cm) is recommended. This provides enough space for both species to establish their own areas and reduces the likelihood of territorial disputes.

What water temperature is best for African Knifefish and Finger Fish together?

Keep the aquarium between 24°C and 28°C. A target of around 26.0°C sits comfortably within both species' preferred ranges.

Are African Knifefish or Finger Fish aggressive?

African Knifefish is moderately assertive (5/10) and Finger Fish is moderately assertive (5/10). Their similar temperaments generally lead to a peaceful coexistence.

What pH do African Knifefish and Finger Fish need?

Both species overlap in the 7.5–7.5 pH range. Consistency is key — avoid sudden swings, and test regularly to stay within this window.

Will Finger Fish nip African Knifefish's fins?

Finger Fish is a known fin nipper. If African Knifefish has long or flowing fins, there is a real risk of fin damage. Keeping Finger Fish in a larger group can help redirect nipping behaviour toward conspecifics.

Does African Knifefish being nocturnal affect compatibility?

African Knifefish is most active after lights-out, which naturally reduces daytime encounters with its tank mate. This can actually be beneficial, as both fish get undisturbed time to feed and explore. Just ensure food reaches African Knifefish during evening hours.


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