Can Fly River Rainbowfish and Red Peacock (Ruby Red) Live Together?

Reviewed by Guidarium Editorial DeskUpdated May 11, 2026
Not Recommended

Fly River Rainbowfish and Red Peacock (Ruby Red) 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

Fly River Rainbowfish

Melanotaenia sexlineata

Red Peacock (Ruby Red)

Aulonocara sp. 'Rubescens'

🐠Family Group
Fly River Rainbowfish
Rainbowfish
Red Peacock (Ruby Red)
Cichlids - African
Temperament
Fly River Rainbowfish
Peaceful (2/10)
Red Peacock (Ruby Red)
Semi-Aggressive (6/10)
Temperature
✓ Compatible
Fly River Rainbowfish
24–28°C
Red Peacock (Ruby Red)
24–28°C
pH Range
✗ No overlap
Fly River Rainbowfish
6–7.5
Red Peacock (Ruby Red)
7.8–8.6
Hardness (dGH)
✓ Compatible
Fly River Rainbowfish
4–15
Red Peacock (Ruby Red)
10–25
Water Type
✓ Compatible
Fly River Rainbowfish
Freshwater Only
Red Peacock (Ruby Red)
Freshwater Only
Flow Preference
✓ Compatible
Fly River Rainbowfish
Moderate
Red Peacock (Ruby Red)
Moderate
Min Tank Volume
Combined: 208 L
Fly River Rainbowfish
110 L
Red Peacock (Ruby Red)
208 L
Swimming Level
Shared: 1 zone
Fly River Rainbowfish
TopMiddle
Red Peacock (Ruby Red)
MiddleBottom
🏷️Behavior Tags
Fly River Rainbowfish
Hyperactive / Fast SwimmerJumper (Lid Required)Aggressive Eater (Starves shy fish)
Red Peacock (Ruby Red)
Digger (Disturbs Substrate)Fry PredatorTerritorial (Defends specific area)Aggressive to same species/look-alikesHyperactive / Fast Swimmer
Stocking calculator

Can your tank handle Fly River Rainbowfish and Red Peacock (Ruby Red)?

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.

Fly River Rainbowfish
Red Peacock (Ruby Red)
Test both in my tank

Behaviour & Temperament

Fly River Rainbowfish is a peaceful species (2/10), while Red Peacock (Ruby Red) is moderately assertive (6/10). This notable difference means Red Peacock (Ruby Red) may occasionally assert dominance over Fly River Rainbowfish.

Fly River Rainbowfish and Red Peacock (Ruby Red) 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.

Worth noting: Fly River Rainbowfish 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.

The pH requirements of Fly River Rainbowfish (6–7.5) and Red Peacock (Ruby Red) (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 Fly River Rainbowfish and Red Peacock (Ruby Red) together, plan for an aquarium of at least 208 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 - lighly covered, Sand (Sifters), Smooth Gravel (Sensitive Barbels). 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

Fly River Rainbowfish and Red Peacock (Ruby Red) 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 Fly River Rainbowfish and Red Peacock (Ruby Red).

Show 5 more tank sizes

Frequently Asked Questions

Can Fly River Rainbowfish and Red Peacock (Ruby Red) live together?

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

What size tank do Fly River Rainbowfish and Red Peacock (Ruby Red) need?

A minimum of 208 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 Fly River Rainbowfish and Red Peacock (Ruby Red) 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 Fly River Rainbowfish or Red Peacock (Ruby Red) aggressive?

Fly River Rainbowfish is peaceful (2/10) and Red Peacock (Ruby Red) 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 Fly River Rainbowfish and Red Peacock (Ruby Red) need?

Their pH requirements do not overlap. Fly River Rainbowfish prefers 6–7.5, while Red Peacock (Ruby Red) needs 7.8–8.6. This makes them incompatible in the same water chemistry.

How do I manage Red Peacock (Ruby Red)'s territorial behaviour?

Provide line-of-sight breaks using rocks, driftwood, and dense planting. A larger tank gives Red Peacock (Ruby Red) 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 11, 2026
Last updated
May 11, 2026
Issues or corrections?
Contact the editorial team

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