Can Figure 8 Puffer (Brackish) and Glass Catfish Live Together?
Figure 8 Puffer (Brackish) and Glass Catfish are not recommended as tank mates due to incompatible water types and 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
Can your tank handle Figure 8 Puffer (Brackish) and Glass 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.
Behaviour & Temperament
Figure 8 Puffer (Brackish) is a semi-aggressive species (8/10), while Glass Catfish is peaceful (1/10). This notable difference means Figure 8 Puffer (Brackish) may occasionally assert dominance over Glass Catfish.
Large aggression gap (7 points) between Figure 8 Puffer (Brackish) and Glass Catfish increases stress risk for the more peaceful fish.
Figure 8 Puffer (Brackish) and Glass Catfish 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: Aggressive fish may bully and stress shy, slow-moving species. Hyperactive swimmers can stress shy, slow-moving species through constant motion.
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 Figure 8 Puffer (Brackish) (7.5–8.5) and Glass Catfish (6–7) do not overlap, making it impossible to satisfy both species simultaneously.
For general hardness, the shared comfort zone is 10–10 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 Figure 8 Puffer (Brackish) and Glass Catfish 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: Sand (Sifters), Shells (Breeding/Hiding), Plants - Densely covered, Plants - Floating. 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
Figure 8 Puffer (Brackish) and Glass 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.
Suitable Tank Sizes
Standard aquarium sizes large enough for both Figure 8 Puffer (Brackish) and Glass Catfish.
30 Gallon Breeder
40 Gallon Breeder
55 Gallon Standard
60 Gallon Breeder
75 Gallon Standard
90 Gallon Standard
Show 10 more tank sizes
Frequently Asked Questions
Can Figure 8 Puffer (Brackish) and Glass Catfish live together?
No. This combination is not recommended. Key incompatibilities — such as different water type needs — make cohabitation unsafe.
What size tank do Figure 8 Puffer (Brackish) and Glass Catfish 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 Figure 8 Puffer (Brackish) and Glass Catfish 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 Figure 8 Puffer (Brackish) or Glass Catfish aggressive?
Figure 8 Puffer (Brackish) is semi-aggressive (8/10) and Glass Catfish is peaceful (1/10). The gap in aggression levels means the calmer fish may experience stress from the more assertive one.
What pH do Figure 8 Puffer (Brackish) and Glass Catfish need?
Their pH requirements do not overlap. Figure 8 Puffer (Brackish) prefers 7.5–8.5, while Glass Catfish needs 6–7. This makes them incompatible in the same water chemistry.
Will Figure 8 Puffer (Brackish) nip Glass Catfish's fins?
Figure 8 Puffer (Brackish) is a known fin nipper. If Glass Catfish has long or flowing fins, there is a real risk of fin damage. Keeping Figure 8 Puffer (Brackish) in a larger group can help redirect nipping behaviour toward conspecifics.
How do I manage Figure 8 Puffer (Brackish)'s territorial behaviour?
Provide line-of-sight breaks using rocks, driftwood, and dense planting. A larger tank gives Figure 8 Puffer (Brackish) 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.
Shared setup supplies
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Guidarium Editorial Desk
Reviewed against Guidarium care, stocking, and compatibility standards. Read the editorial policy.
- Last reviewed
- April 28, 2026
- Last updated
- April 28, 2026
- Issues or corrections?
- Contact the editorial team
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