Can Black Ruby Barb and Fosso Cichlid (Fossorochromis rostratus) Live Together?

Reviewed by Guidarium Editorial DeskUpdated May 6, 2026
Not Recommended

Black Ruby Barb and Fosso Cichlid (Fossorochromis rostratus) 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

Black Ruby Barb

Pethia nigrofasciata

Fosso Cichlid (Fossorochromis rostratus)

Fossorochromis rostratus

🐠Family Group
Black Ruby Barb
Cyprinids
Fosso Cichlid (Fossorochromis rostratus)
Cichlids - African
Temperament
Black Ruby Barb
Mostly Peaceful (3/10)
Fosso Cichlid (Fossorochromis rostratus)
Semi-Aggressive (6/10)
Temperature
✓ Compatible
Black Ruby Barb
20–26°C
Fosso Cichlid (Fossorochromis rostratus)
24–28°C
pH Range
✗ No overlap
Black Ruby Barb
5.5–7.5
Fosso Cichlid (Fossorochromis rostratus)
7.8–8.6
Hardness (dGH)
✓ Compatible
Black Ruby Barb
2–15
Fosso Cichlid (Fossorochromis rostratus)
10–25
Water Type
✓ Compatible
Black Ruby Barb
Freshwater Only
Fosso Cichlid (Fossorochromis rostratus)
Freshwater Only
Flow Preference
✓ Compatible
Black Ruby Barb
Moderate
Fosso Cichlid (Fossorochromis rostratus)
Moderate
Min Tank Volume
Combined: 680 L
Black Ruby Barb
80 L
Fosso Cichlid (Fossorochromis rostratus)
680 L
Swimming Level
Shared: 2 zones
Black Ruby Barb
MiddleBottom
Fosso Cichlid (Fossorochromis rostratus)
BottomMiddle
🏷️Behavior Tags
Black Ruby Barb
Hyperactive / Fast SwimmerFry PredatorAggressive Eater (Starves shy fish)
Fosso Cichlid (Fossorochromis rostratus)
Digger (Disturbs Substrate)Territorial (Defends specific area)Hyperactive / Fast SwimmerPiscivore (Eats small/nano fish)
Stocking calculator

Can your tank handle Black Ruby Barb and Fosso Cichlid (Fossorochromis rostratus)?

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.

Black Ruby Barb
Fosso Cichlid (Fossorochromis rostratus)
Test both in my tank

Behaviour & Temperament

Black Ruby Barb is a generally mild-mannered species (3/10), while Fosso Cichlid (Fossorochromis rostratus) is moderately assertive (6/10). This modest difference means Fosso Cichlid (Fossorochromis rostratus) may occasionally assert dominance over Black Ruby Barb.

Black Ruby Barb and Fosso Cichlid (Fossorochromis rostratus) both frequent the Middle (Open Water) and Bottom (Substrate) region of the setup. This overlap can increase competition for space, so providing ample room and cover is important to keep both species comfortable.

Water Parameters

The safe temperature window for both species falls between 24°C and 26°C. Aim for the midpoint of this range (around 25.0°C) for optimal comfort.

The pH requirements of Black Ruby Barb (5.5–7.5) and Fosso Cichlid (Fossorochromis rostratus) (7.8–8.6) 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 Black Ruby Barb and Fosso Cichlid (Fossorochromis rostratus) together, plan for an aquarium of at least 680 litres with a minimum length of 180 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, Leaf Litter/Blackwater, Driftwood (Digestion/Hiding), Sand (Sifters). 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

Black Ruby Barb and Fosso Cichlid (Fossorochromis rostratus) 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 Black Ruby Barb and Fosso Cichlid (Fossorochromis rostratus).

Frequently Asked Questions

Can Black Ruby Barb and Fosso Cichlid (Fossorochromis rostratus) live together?

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

What size tank do Black Ruby Barb and Fosso Cichlid (Fossorochromis rostratus) need?

A minimum of 680 litres (tank length at least 180 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 Black Ruby Barb and Fosso Cichlid (Fossorochromis rostratus) together?

Keep the aquarium between 24°C and 26°C. A target of around 25.0°C sits comfortably within both species' preferred ranges.

Are Black Ruby Barb or Fosso Cichlid (Fossorochromis rostratus) aggressive?

Black Ruby Barb is generally mild-mannered (3/10) and Fosso Cichlid (Fossorochromis rostratus) is moderately assertive (6/10). Their similar temperaments generally lead to a peaceful coexistence.

What pH do Black Ruby Barb and Fosso Cichlid (Fossorochromis rostratus) need?

Their pH requirements do not overlap. Black Ruby Barb prefers 5.5–7.5, while Fosso Cichlid (Fossorochromis rostratus) needs 7.8–8.6. This makes them incompatible in the same water chemistry.

How do I manage Fosso Cichlid (Fossorochromis rostratus)'s territorial behaviour?

Provide line-of-sight breaks using rocks, driftwood, and dense planting. A larger tank gives Fosso Cichlid (Fossorochromis rostratus) 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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