Can Marlier's Julie and Monster Wolf Fish (Aimara) Live Together?

Reviewed by Guidarium Editorial DeskUpdated May 6, 2026
Not Recommended

Marlier's Julie and Monster Wolf Fish (Aimara) are not recommended as tank mates due to conflicting pH requirements. Housing these species together is likely to result in stress, health problems, or direct harm to one or both fish.


At a Glance

Marlier's Julie

Julidochromis marlieri

Monster Wolf Fish (Aimara)

Hoplias aimara

🐠Family Group
Marlier's Julie
Cichlids - African
Monster Wolf Fish (Aimara)
Oddballs
Temperament
Marlier's Julie
Semi-Aggressive (6/10)
Monster Wolf Fish (Aimara)
Highly Aggressive (10/10)
Temperature
✓ Compatible
Marlier's Julie
23–27°C
Monster Wolf Fish (Aimara)
23–28°C
pH Range
✗ No overlap
Marlier's Julie
8.2–9.3
Monster Wolf Fish (Aimara)
6–7.5
Hardness (dGH)
✓ Compatible
Marlier's Julie
10–25
Monster Wolf Fish (Aimara)
2–15
Water Type
✓ Compatible
Marlier's Julie
Freshwater Only
Monster Wolf Fish (Aimara)
Freshwater Only
Flow Preference
✓ Compatible
Marlier's Julie
Moderate
Monster Wolf Fish (Aimara)
High
Min Tank Volume
Combined: 1500 L
Marlier's Julie
114 L
Monster Wolf Fish (Aimara)
1500 L
Swimming Level
Shared: 2 zones
Marlier's Julie
BottomMiddle
Monster Wolf Fish (Aimara)
MiddleBottom
🏷️Behavior Tags
Marlier's Julie
Territorial (Defends specific area)Aggressive to same species/look-alikesDigger (Disturbs Substrate)Fry Predator
Monster Wolf Fish (Aimara)
Piscivore (Eats small/nano fish)Generally AggressiveAggressive to same species/look-alikesTerritorial (Defends specific area)Jumper (Lid Required)Hyperactive / Fast Swimmer
Stocking calculator

Can your tank handle Marlier's Julie and Monster Wolf Fish (Aimara)?

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.

Marlier's Julie
Monster Wolf Fish (Aimara)
Test both in my tank

Behaviour & Temperament

Marlier's Julie is a moderately assertive species (6/10), while Monster Wolf Fish (Aimara) is highly aggressive (10/10). This notable difference means Monster Wolf Fish (Aimara) may occasionally assert dominance over Marlier's Julie.

Marlier's Julie and Monster Wolf Fish (Aimara) both frequent the Bottom (Substrate) and 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: Two territorial species may clash over territory, especially in smaller tanks.

Worth noting: Monster Wolf Fish (Aimara) 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 27°C. Aim for the midpoint of this range (around 25.0°C) for optimal comfort.

The pH requirements of Marlier's Julie (8.2–9.3) and Monster Wolf Fish (Aimara) (6–7.5) do not overlap, making it impossible to satisfy both species simultaneously.

For general hardness, the shared comfort zone is 10–15 dGH. Regular testing will ensure conditions stay within this range.

Tank Setup

To house Marlier's Julie and Monster Wolf Fish (Aimara) together, plan for an aquarium of at least 1500 litres with a minimum length of 240 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: 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

Marlier's Julie and Monster Wolf Fish (Aimara) 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.

Frequently Asked Questions

Can Marlier's Julie and Monster Wolf Fish (Aimara) live together?

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

What size tank do Marlier's Julie and Monster Wolf Fish (Aimara) need?

A minimum of 1500 litres (tank length at least 240 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 Marlier's Julie and Monster Wolf Fish (Aimara) together?

Keep the aquarium between 23°C and 27°C. A target of around 25.0°C sits comfortably within both species' preferred ranges.

Are Marlier's Julie or Monster Wolf Fish (Aimara) aggressive?

Marlier's Julie is moderately assertive (6/10) and Monster Wolf Fish (Aimara) is highly aggressive (10/10). The gap in aggression levels means the calmer fish may experience stress from the more assertive one.

What pH do Marlier's Julie and Monster Wolf Fish (Aimara) need?

Their pH requirements do not overlap. Marlier's Julie prefers 8.2–9.3, while Monster Wolf Fish (Aimara) needs 6–7.5. This makes them incompatible in the same water chemistry.

How do I manage Marlier's Julie's territorial behaviour?

Provide line-of-sight breaks using rocks, driftwood, and dense planting. A larger tank gives Marlier's Julie space to claim a territory without encroaching on the other fish's area. Adding décor that divides the tank into distinct zones works especially well.

Editorial Review

Guidarium Editorial Desk

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

Last reviewed
May 6, 2026
Last updated
May 6, 2026
Issues or corrections?
Contact the editorial team

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