Can African Knifefish and Pacific Blue Eye Live Together?

Not Recommended

African Knifefish and Pacific Blue Eye are not recommended as tank mates due to piscivorous fish will prey on nano-sized tank mates.. 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

Pacific Blue Eye

Pseudomugil signifer

🐠Family Group
African Knifefish
Oddballs
Pacific Blue Eye
Rainbowfish
Temperament
African Knifefish
Semi-Aggressive (5/10)
Pacific Blue Eye
Peaceful (2/10)
Temperature
✓ Compatible
African Knifefish
23–28°C
Pacific Blue Eye
20–26°C
pH Range
✓ Compatible
African Knifefish
6–7.5
Pacific Blue Eye
6.5–8
Hardness (dGH)
✓ Compatible
African Knifefish
2–15
Pacific Blue Eye
5–15
Water Type
✓ Compatible
African Knifefish
Freshwater Only
Pacific Blue Eye
Brackish Tolerant
Flow Preference
✓ Compatible
African Knifefish
Low
Pacific Blue Eye
Moderate
Min Tank Volume
Combined: 200 L
African Knifefish
200 L
Pacific Blue Eye
60 L
Swimming Level
Shared: 1 zone
African Knifefish
MiddleBottom
Pacific Blue Eye
TopMiddle
🏷️Behavior Tags
African Knifefish
Piscivore (Eats small/nano fish)Shrimp EaterNocturnalShy / Slow Moving (Easily Stressed)Aggressive to same species/look-alikes
Pacific Blue Eye
Nano / Bite-sized (Predation Risk)Hyperactive / Fast SwimmerJumper (Lid Required)Fry Predator
Stocking calculator

Can your tank handle African Knifefish and Pacific Blue Eye?

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
Pacific Blue Eye
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Behaviour & Temperament

African Knifefish is a moderately assertive species (5/10), while Pacific Blue Eye is peaceful (2/10). This modest difference means African Knifefish may occasionally assert dominance over Pacific Blue Eye.

African Knifefish and Pacific Blue Eye 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.

There is a critical concern: the Piscivore (Eats small/nano fish) behaviour of one fish directly conflicts with the Nano / Bite-sized (Predation Risk) trait of the other — piscivorous fish will prey on nano-sized tank mates..

Additional behavioural considerations to keep in mind: Hyperactive swimmers can stress shy, slow-moving species through constant motion. Shrimp eaters may also prey on very small nano fish.

Worth noting: African Knifefish is nocturnal and will be most active after lights-out, naturally reducing daytime encounters. Also, Pacific Blue Eye is a known jumper, so a tight-fitting lid is essential.

Water Parameters

The safe temperature window for both species falls between 23°C and 26°C. Aim for the midpoint of this range (around 24.5°C) for optimal comfort.

Both fish can tolerate a pH between 6.5 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 5–15 dGH. Regular testing will ensure conditions stay within this range.

Tank Setup

To house African Knifefish and Pacific Blue Eye 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.

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, Plants - Densely covered. 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 Pacific Blue Eye.

Show 5 more tank sizes

Diet & Feeding

Feeding time deserves special attention with this pairing. African Knifefish is a known shrimp eater and may prey on small invertebrates or nano fish like Pacific Blue Eye.

Frequently Asked Questions

Can African Knifefish and Pacific Blue Eye live together?

No. This combination is not recommended. Key incompatibilities — such as critical behavioural conflicts — make cohabitation unsafe.

What size tank do African Knifefish and Pacific Blue Eye 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 Pacific Blue Eye together?

Keep the aquarium between 23°C and 26°C. A target of around 24.5°C sits comfortably within both species' preferred ranges.

Are African Knifefish or Pacific Blue Eye aggressive?

African Knifefish is moderately assertive (5/10) and Pacific Blue Eye is peaceful (2/10). Their similar temperaments generally lead to a peaceful coexistence.

What pH do African Knifefish and Pacific Blue Eye need?

Both species overlap in the 6.5–7.5 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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