Can African Knifefish and Silver Hatchetfish Live Together?

Possible with Caution

Keeping African Knifefish and Silver Hatchetfish together is possible but requires caution due to differing aggression levels and potential behavioral clashes. Provide a spacious tank of at least 200 litres with plenty of hiding spots to reduce stress. Monitor behaviour closely, especially during the first few weeks.


At a Glance

African Knifefish

Xenomystus nigri

Silver Hatchetfish

Gasteropelecus sternicla

🐠Family Group
African Knifefish
Oddballs
Silver Hatchetfish
Characins
Temperament
African Knifefish
Semi-Aggressive (5/10)
Silver Hatchetfish
Peaceful (1/10)
Temperature
✓ Compatible
African Knifefish
23–28°C
Silver Hatchetfish
23–28°C
pH Range
✓ Compatible
African Knifefish
6–7.5
Silver Hatchetfish
6–7.5
Hardness (dGH)
✓ Compatible
African Knifefish
2–15
Silver Hatchetfish
2–12
Water Type
✓ Compatible
African Knifefish
Freshwater Only
Silver Hatchetfish
Freshwater Only
Flow Preference
✓ Compatible
African Knifefish
Low
Silver Hatchetfish
Moderate
Min Tank Volume
Combined: 200 L
African Knifefish
200 L
Silver Hatchetfish
75 L
Swimming Level
✓ Different zones
African Knifefish
MiddleBottom
Silver Hatchetfish
Top
🏷️Behavior Tags
African Knifefish
Piscivore (Eats small/nano fish)Shrimp EaterNocturnalShy / Slow Moving (Easily Stressed)Aggressive to same species/look-alikes
Silver Hatchetfish
Jumper (Lid Required)Shy / Slow Moving (Easily Stressed)Hyperactive / Fast Swimmer
Stocking calculator

Can your tank handle African Knifefish and Silver Hatchetfish?

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
Silver Hatchetfish
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Behaviour & Temperament

African Knifefish is a moderately assertive species (5/10), while Silver Hatchetfish is peaceful (1/10). This notable difference means African Knifefish may occasionally assert dominance over Silver Hatchetfish.

In terms of spatial distribution, African Knifefish prefers the Middle (Open Water) and Bottom (Substrate) zones, whereas Silver Hatchetfish occupies the Top (Surface) zone. Because they use different levels of the water column, territorial disputes are less likely and the tank will appear more balanced.

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. Also, Silver Hatchetfish is a known jumper, so a tight-fitting lid is essential.

To improve the chances of a peaceful coexistence in this community tank: A larger aquarium with ample hiding spots can help diffuse aggression and give the less dominant fish space to retreat.

Water Parameters

The safe temperature window for both species falls between 23°C and 28°C. Aim for the midpoint of this range (around 25.5°C) for optimal comfort.

Both fish can tolerate a pH between 6 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 2–12 dGH. Regular testing will ensure conditions stay within this range.

Tank Setup

To house African Knifefish and Silver Hatchetfish together, plan for an aquarium of at least 200 litres with a minimum length of 120 cm. This recommendation combines the stricter species minimums with a community-load allowance so the pairing has realistic long-term space and filtration headroom.

Because this pairing requires extra vigilance, include plenty of hiding spots — caves, driftwood, and dense plant clusters — so the less dominant fish can retreat when needed.

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 Silver Hatchetfish.

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Frequently Asked Questions

Can African Knifefish and Silver Hatchetfish live together?

They can coexist, but the pairing requires careful monitoring. Provide ample space (at least 200 litres), plenty of hiding spots, and watch for signs of stress or aggression.

What size tank do African Knifefish and Silver Hatchetfish need?

A minimum of 200 litres (tank length at least 120 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 Silver Hatchetfish together?

Keep the aquarium between 23°C and 28°C. A target of around 25.5°C sits comfortably within both species' preferred ranges.

Are African Knifefish or Silver Hatchetfish aggressive?

African Knifefish is moderately assertive (5/10) and Silver Hatchetfish is peaceful (1/10). The gap in aggression levels means the calmer fish may experience stress from the more assertive one.

What pH do African Knifefish and Silver Hatchetfish need?

Both species overlap in the 6–7.5 pH range. Consistency is key — avoid sudden swings, and test regularly to stay within this window.

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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