Can Gertrude's Spotted Blue-eye and Mokele-mbembe Bichir Live Together?

Reviewed by Guidarium Editorial DeskUpdated May 7, 2026
Not Recommended

Gertrude's Spotted Blue-eye and Mokele-mbembe Bichir 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

Gertrude's Spotted Blue-eye

Pseudomugil gertrudae

Mokele-mbembe Bichir

Polypterus mokelembembe

🐠Family Group
Gertrude's Spotted Blue-eye
Rainbowfish
Mokele-mbembe Bichir
Oddballs
Temperament
Gertrude's Spotted Blue-eye
Peaceful (2/10)
Mokele-mbembe Bichir
Semi-Aggressive (6/10)
Temperature
✓ Compatible
Gertrude's Spotted Blue-eye
21–28°C
Mokele-mbembe Bichir
24–28°C
pH Range
✓ Compatible
Gertrude's Spotted Blue-eye
6–7.5
Mokele-mbembe Bichir
6.5–7.5
Hardness (dGH)
✓ Compatible
Gertrude's Spotted Blue-eye
5–15
Mokele-mbembe Bichir
5–19
Water Type
✓ Compatible
Gertrude's Spotted Blue-eye
Freshwater Only
Mokele-mbembe Bichir
Freshwater Only
Flow Preference
✓ Compatible
Gertrude's Spotted Blue-eye
Moderate
Mokele-mbembe Bichir
Low
Min Tank Volume
Combined: 200 L
Gertrude's Spotted Blue-eye
38 L
Mokele-mbembe Bichir
200 L
Swimming Level
✓ Different zones
Gertrude's Spotted Blue-eye
TopMiddle
Mokele-mbembe Bichir
Bottom
🏷️Behavior Tags
Gertrude's Spotted Blue-eye
Nano / Bite-sized (Predation Risk)Hyperactive / Fast SwimmerJumper (Lid Required)Fry Predator
Mokele-mbembe Bichir
Piscivore (Eats small/nano fish)Shrimp EaterFry PredatorJumper (Lid Required)Nocturnal
Stocking calculator

Can your tank handle Gertrude's Spotted Blue-eye and Mokele-mbembe Bichir?

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.

Gertrude's Spotted Blue-eye
Mokele-mbembe Bichir
Test both in my tank

Behaviour & Temperament

Gertrude's Spotted Blue-eye is a peaceful species (2/10), while Mokele-mbembe Bichir is moderately assertive (6/10). This notable difference means Mokele-mbembe Bichir may occasionally assert dominance over Gertrude's Spotted Blue-eye.

In terms of spatial distribution, Gertrude's Spotted Blue-eye prefers the Top (Surface) and Middle (Open Water) zones, whereas Mokele-mbembe Bichir occupies the Bottom (Substrate) zone. Because they use different levels of the water column, territorial disputes are less likely and the tank will appear more balanced.

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

Additional behavioural considerations to keep in mind: Shrimp eaters may also prey on very small nano fish.

Worth noting: Mokele-mbembe Bichir is nocturnal and will be most active after lights-out, naturally reducing daytime encounters. Also, Gertrude's Spotted Blue-eye is a known jumper, so a tight-fitting lid is essential.

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 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 Gertrude's Spotted Blue-eye and Mokele-mbembe Bichir 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: Plants - Densely covered, Plants - Floating, Leaf Litter/Blackwater, Sand (Sifters), Smooth Gravel (Sensitive Barbels), Driftwood (Digestion/Hiding). Meeting these requirements will help both species thrive.

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

Why This Pairing Usually Fails in Practice

Gertrude's Spotted Blue-eye and Mokele-mbembe Bichir are the kind of pair that can look acceptable in a shop but become a maintenance problem at home. The main risk is not a single number in the chart; it is the way incompatible behavior, water needs, or pressure on space compounds over time once both fish are established in the same tank.

Suitable Tank Sizes

Standard aquarium sizes large enough for both Gertrude's Spotted Blue-eye and Mokele-mbembe Bichir.

Show 5 more tank sizes

Diet & Feeding

Feeding time deserves special attention with this pairing. Mokele-mbembe Bichir is a known shrimp eater and may prey on small invertebrates or nano fish like Gertrude's Spotted Blue-eye.

Frequently Asked Questions

Can Gertrude's Spotted Blue-eye and Mokele-mbembe Bichir live together?

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

What size tank do Gertrude's Spotted Blue-eye and Mokele-mbembe Bichir 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 Gertrude's Spotted Blue-eye and Mokele-mbembe Bichir 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 Gertrude's Spotted Blue-eye or Mokele-mbembe Bichir aggressive?

Gertrude's Spotted Blue-eye is peaceful (2/10) and Mokele-mbembe Bichir is moderately assertive (6/10). The gap in aggression levels means the calmer fish may experience stress from the more assertive one.

What pH do Gertrude's Spotted Blue-eye and Mokele-mbembe Bichir 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 Mokele-mbembe Bichir being nocturnal affect compatibility?

Mokele-mbembe Bichir 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 Mokele-mbembe Bichir during evening hours.

Editorial Review

Guidarium Editorial Desk

Reviewed against Guidarium care, stocking, and compatibility standards. Read the editorial policy.

Last reviewed
May 7, 2026
Last updated
May 7, 2026
Issues or corrections?
Contact the editorial team

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