Can Blue Back Blue Eye and Red-Tail Catfish Live Together?

Reviewed by Guidarium Editorial DeskUpdated May 2, 2026
Not Recommended

Blue Back Blue Eye and Red-Tail Catfish are not recommended as tank mates due to incompatible water types and 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

Blue Back Blue Eye

Pseudomugil cyanodorsalis

Red-Tail Catfish

Phractocephalus hemioliopterus

🐠Family Group
Blue Back Blue Eye
Rainbowfish
Red-Tail Catfish
Catfish
Temperament
Blue Back Blue Eye
Peaceful (2/10)
Red-Tail Catfish
Aggressive (7/10)
Temperature
✓ Compatible
Blue Back Blue Eye
22–30°C
Red-Tail Catfish
20–28°C
pH Range
✓ Compatible
Blue Back Blue Eye
7–8.5
Red-Tail Catfish
6–7.5
Hardness (dGH)
✓ Compatible
Blue Back Blue Eye
10–30
Red-Tail Catfish
3–15
Water Type
✗ No overlap
Blue Back Blue Eye
Brackish Required
Red-Tail Catfish
Freshwater Only
Flow Preference
✓ Compatible
Blue Back Blue Eye
Moderate
Red-Tail Catfish
Moderate
Min Tank Volume
Combined: 3800 L
Blue Back Blue Eye
38 L
Red-Tail Catfish
3800 L
Swimming Level
✓ Different zones
Blue Back Blue Eye
TopMiddle
Red-Tail Catfish
Bottom
🏷️Behavior Tags
Blue Back Blue Eye
Nano / Bite-sized (Predation Risk)Jumper (Lid Required)Hyperactive / Fast SwimmerFry Predator
Red-Tail Catfish
Piscivore (Eats small/nano fish)Plant DestroyerDigger (Disturbs Substrate)Nocturnal
Stocking calculator

Can your tank handle Blue Back Blue Eye and Red-Tail Catfish?

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.

Blue Back Blue Eye
Red-Tail Catfish
Test both in my tank

Behaviour & Temperament

Blue Back Blue Eye is a peaceful species (2/10), while Red-Tail Catfish is semi-aggressive (7/10). This notable difference means Red-Tail Catfish may occasionally assert dominance over Blue Back Blue Eye.

In terms of spatial distribution, Blue Back Blue Eye prefers the Top (Surface) and Middle (Open Water) zones, whereas Red-Tail Catfish 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..

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

Water Parameters

The safe temperature window for both species falls between 22°C and 28°C. Aim for the midpoint of this range (around 25.0°C) for optimal comfort.

Both fish can tolerate a pH between 7 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 10–15 dGH. Regular testing will ensure conditions stay within this range.

Crucially, these species require different water types — one needs freshwater while the other requires brackish conditions. This is a hard barrier to keeping them together.

Tank Setup

To house Blue Back Blue Eye and Red-Tail Catfish together, plan for an aquarium of at least 3800 litres with a minimum length of 300 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), 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

Blue Back Blue Eye and Red-Tail Catfish 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 Blue Back Blue Eye and Red-Tail Catfish live together?

No. This combination is not recommended. Key incompatibilities — such as different water type needs — make cohabitation unsafe.

What size tank do Blue Back Blue Eye and Red-Tail Catfish need?

A minimum of 3800 litres (tank length at least 300 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 Blue Back Blue Eye and Red-Tail Catfish together?

Keep the aquarium between 22°C and 28°C. A target of around 25.0°C sits comfortably within both species' preferred ranges.

Are Blue Back Blue Eye or Red-Tail Catfish aggressive?

Blue Back Blue Eye is peaceful (2/10) and Red-Tail Catfish is semi-aggressive (7/10). The gap in aggression levels means the calmer fish may experience stress from the more assertive one.

What pH do Blue Back Blue Eye and Red-Tail Catfish need?

Both species overlap in the 7–7.5 pH range. Consistency is key — avoid sudden swings, and test regularly to stay within this window.

Does Red-Tail Catfish being nocturnal affect compatibility?

Red-Tail Catfish 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 Red-Tail Catfish during evening hours.

Editorial Review

Guidarium Editorial Desk

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

Last reviewed
May 2, 2026
Last updated
May 2, 2026
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