Can Festivum and Figure 8 Puffer (Brackish) Live Together?
Festivum and Figure 8 Puffer (Brackish) 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 Festivum and Figure 8 Puffer (Brackish)?
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
Festivum is a generally mild-mannered species (4/10), while Figure 8 Puffer (Brackish) is semi-aggressive (8/10). This notable difference means Figure 8 Puffer (Brackish) may occasionally assert dominance over Festivum.
Festivum and Figure 8 Puffer (Brackish) 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: Two territorial species may clash over territory, especially in smaller tanks.
Worth noting: Festivum 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 Festivum (5.5–7.2) and Figure 8 Puffer (Brackish) (7.5–8.5) do not overlap, making it impossible to satisfy both species simultaneously.
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 Festivum and Figure 8 Puffer (Brackish) together, plan for an aquarium of at least 150 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: Driftwood (Digestion/Hiding), Plants - Floating, Sand (Sifters), Shells (Breeding/Hiding). 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
Festivum and Figure 8 Puffer (Brackish) 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 Festivum and Figure 8 Puffer (Brackish).
40 Gallon Breeder
55 Gallon Standard
60 Gallon Breeder
75 Gallon Standard
90 Gallon Standard
125 Gallon Standard
Show 9 more tank sizes
Frequently Asked Questions
Can Festivum and Figure 8 Puffer (Brackish) live together?
No. This combination is not recommended. Key incompatibilities — such as different water type needs — make cohabitation unsafe.
What size tank do Festivum and Figure 8 Puffer (Brackish) need?
A minimum of 150 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 Festivum and Figure 8 Puffer (Brackish) 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 Festivum or Figure 8 Puffer (Brackish) aggressive?
Festivum is generally mild-mannered (4/10) and Figure 8 Puffer (Brackish) is semi-aggressive (8/10). The gap in aggression levels means the calmer fish may experience stress from the more assertive one.
What pH do Festivum and Figure 8 Puffer (Brackish) need?
Their pH requirements do not overlap. Festivum prefers 5.5–7.2, while Figure 8 Puffer (Brackish) needs 7.5–8.5. This makes them incompatible in the same water chemistry.
Will Figure 8 Puffer (Brackish) nip Festivum's fins?
Figure 8 Puffer (Brackish) is a known fin nipper. If Festivum 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 Festivum's territorial behaviour?
Provide line-of-sight breaks using rocks, driftwood, and dense planting. A larger tank gives Festivum 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.
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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?
- Contact the editorial team
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