Can Blue Back Blue Eye and Flagtail Cory (Mrs Schwartz's Cory) Live Together?

Reviewed by Guidarium Editorial DeskUpdated May 6, 2026
Not Recommended

Blue Back Blue Eye and Flagtail Cory (Mrs Schwartz's Cory) are not recommended as tank mates due to incompatible water types. 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

Flagtail Cory (Mrs Schwartz's Cory)

Corydoras robineae

🐠Family Group
Blue Back Blue Eye
Rainbowfish
Flagtail Cory (Mrs Schwartz's Cory)
Catfish
Temperament
Blue Back Blue Eye
Peaceful (2/10)
Flagtail Cory (Mrs Schwartz's Cory)
Peaceful (1/10)
Temperature
✓ Compatible
Blue Back Blue Eye
22–30°C
Flagtail Cory (Mrs Schwartz's Cory)
24–28°C
pH Range
✓ Compatible
Blue Back Blue Eye
7–8.5
Flagtail Cory (Mrs Schwartz's Cory)
6–7.5
Hardness (dGH)
✓ Compatible
Blue Back Blue Eye
10–30
Flagtail Cory (Mrs Schwartz's Cory)
2–12
Water Type
✗ No overlap
Blue Back Blue Eye
Brackish Required
Flagtail Cory (Mrs Schwartz's Cory)
Freshwater Only
Flow Preference
✓ Compatible
Blue Back Blue Eye
Moderate
Flagtail Cory (Mrs Schwartz's Cory)
Moderate
Min Tank Volume
Combined: 60 L
Blue Back Blue Eye
38 L
Flagtail Cory (Mrs Schwartz's Cory)
60 L
Swimming Level
✓ Different zones
Blue Back Blue Eye
TopMiddle
Flagtail Cory (Mrs Schwartz's Cory)
Bottom
🏷️Behavior Tags
Blue Back Blue Eye
Nano / Bite-sized (Predation Risk)Jumper (Lid Required)Hyperactive / Fast SwimmerFry Predator
Flagtail Cory (Mrs Schwartz's Cory)
Hyperactive / Fast SwimmerShy / Slow Moving (Easily Stressed)
Stocking calculator

Can your tank handle Blue Back Blue Eye and Flagtail Cory (Mrs Schwartz's Cory)?

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
Flagtail Cory (Mrs Schwartz's Cory)
Test both in my tank

Behaviour & Temperament

Blue Back Blue Eye is a peaceful species (2/10), while Flagtail Cory (Mrs Schwartz's Cory) is peaceful (1/10). This modest difference means Blue Back Blue Eye may occasionally assert dominance over Flagtail Cory (Mrs Schwartz's Cory).

In terms of spatial distribution, Blue Back Blue Eye prefers the Top (Surface) and Middle (Open Water) zones, whereas Flagtail Cory (Mrs Schwartz's Cory) 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.

Additional behavioural considerations to keep in mind: Hyperactive swimmers can stress shy, slow-moving species through constant motion.

Worth noting: 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 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 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 10–12 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 Flagtail Cory (Mrs Schwartz's Cory) together, plan for an aquarium of at least 60 litres with a minimum length of 60 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), Leaf Litter/Blackwater. 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 Flagtail Cory (Mrs Schwartz's Cory) 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 Blue Back Blue Eye and Flagtail Cory (Mrs Schwartz's Cory).

Show 19 more tank sizes

Frequently Asked Questions

Can Blue Back Blue Eye and Flagtail Cory (Mrs Schwartz's Cory) 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 Flagtail Cory (Mrs Schwartz's Cory) need?

A minimum of 60 litres (tank length at least 60 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 Flagtail Cory (Mrs Schwartz's Cory) 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 Blue Back Blue Eye or Flagtail Cory (Mrs Schwartz's Cory) aggressive?

Blue Back Blue Eye is peaceful (2/10) and Flagtail Cory (Mrs Schwartz's Cory) is peaceful (1/10). Their similar temperaments generally lead to a peaceful coexistence.

What pH do Blue Back Blue Eye and Flagtail Cory (Mrs Schwartz's Cory) 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.

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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