Can False Glass Catfish and Florida Flagfish Live Together?

Reviewed by Guidarium Editorial DeskUpdated May 4, 2026
Not Recommended

False Glass Catfish and Florida Flagfish are not recommended as tank mates due to incompatible hardness ranges. Housing these species together is likely to result in stress, health problems, or direct harm to one or both fish.


At a Glance

False Glass Catfish

Kryptopterus macrocephalus

Florida Flagfish

Jordanella floridae

🐠Family Group
False Glass Catfish
Catfish
Florida Flagfish
Killifish
Temperament
False Glass Catfish
Peaceful (2/10)
Florida Flagfish
Semi-Aggressive (5/10)
Temperature
✓ Compatible
False Glass Catfish
22–28°C
Florida Flagfish
18–26°C
pH Range
✓ Compatible
False Glass Catfish
5–7
Florida Flagfish
6.5–8.5
Hardness (dGH)
✗ No overlap
False Glass Catfish
1–8
Florida Flagfish
10–25
Water Type
✓ Compatible
False Glass Catfish
Freshwater Only
Florida Flagfish
Brackish Tolerant
Flow Preference
✓ Compatible
False Glass Catfish
Low
Florida Flagfish
Low
Min Tank Volume
Combined: 110 L
False Glass Catfish
110 L
Florida Flagfish
75 L
Swimming Level
Shared: 1 zone
False Glass Catfish
Middle
Florida Flagfish
MiddleBottom
🏷️Behavior Tags
False Glass Catfish
Shy / Slow Moving (Easily Stressed)Fry PredatorShrimp Eater
Florida Flagfish
Fin NipperAggressive to same species/look-alikesHyperactive / Fast SwimmerTerritorial (Defends specific area)
Stocking calculator

Can your tank handle False Glass Catfish and Florida Flagfish?

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.

False Glass Catfish
Florida Flagfish
Test both in my tank

Behaviour & Temperament

False Glass Catfish is a peaceful species (2/10), while Florida Flagfish is moderately assertive (5/10). This modest difference means Florida Flagfish may occasionally assert dominance over False Glass Catfish.

False Glass Catfish and Florida Flagfish 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.

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

Water Parameters

The safe temperature window for both species falls between 22°C and 26°C. Aim for the midpoint of this range (around 24.0°C) for optimal comfort.

Both fish can tolerate a pH between 6.5 and 7. Maintaining a stable value within this band is more important than hitting an exact number.

Hardness requirements are incompatible: False Glass Catfish needs 1–8 dGH while Florida Flagfish requires 10–25 dGH.

Tank Setup

To house False Glass Catfish and Florida Flagfish together, plan for an aquarium of at least 110 litres with a minimum length of 90 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 - Floating, Leaf Litter/Blackwater, Established Algae (Otocinclus). Meeting these requirements will help both species thrive.

Both species do well with low (still water) water movement, so a standard filtration setup rated for the tank volume should suffice.

Why This Pairing Usually Fails in Practice

False Glass Catfish and Florida Flagfish 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 False Glass Catfish and Florida Flagfish.

Show 10 more tank sizes

Frequently Asked Questions

Can False Glass Catfish and Florida Flagfish live together?

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

What size tank do False Glass Catfish and Florida Flagfish need?

A minimum of 110 litres (tank length at least 90 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 False Glass Catfish and Florida Flagfish together?

Keep the aquarium between 22°C and 26°C. A target of around 24.0°C sits comfortably within both species' preferred ranges.

Are False Glass Catfish or Florida Flagfish aggressive?

False Glass Catfish is peaceful (2/10) and Florida Flagfish is moderately assertive (5/10). Their similar temperaments generally lead to a peaceful coexistence.

What pH do False Glass Catfish and Florida Flagfish need?

Both species overlap in the 6.5–7 pH range. Consistency is key — avoid sudden swings, and test regularly to stay within this window.

Will Florida Flagfish nip False Glass Catfish's fins?

Florida Flagfish is a known fin nipper. If False Glass Catfish has long or flowing fins, there is a real risk of fin damage. Keeping Florida Flagfish in a larger group can help redirect nipping behaviour toward conspecifics.

How do I manage Florida Flagfish's territorial behaviour?

Provide line-of-sight breaks using rocks, driftwood, and dense planting. A larger tank gives Florida Flagfish 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 4, 2026
Last updated
May 4, 2026
Issues or corrections?
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