Can Gardner's Killifish and Green Spotted Puffer (Brackish) Live Together?
Gardner's Killifish and Green Spotted Puffer (Brackish) are not recommended as tank mates due to incompatible water types and 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
Behaviour & Temperament
Gardner's Killifish is a generally mild-mannered species (4/10), while Green Spotted Puffer (Brackish) is highly aggressive (9/10). This notable difference means Green Spotted Puffer (Brackish) may occasionally assert dominance over Gardner's Killifish.
Gardner's Killifish and Green Spotted 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.
Worth noting: Gardner's Killifish 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 26°C. Aim for the midpoint of this range (around 25.0°C) for optimal comfort.
Both fish can tolerate a pH between 7.5 and 7.5. Maintaining a stable value within this band is more important than hitting an exact number.
Hardness requirements are incompatible: Gardner's Killifish needs 4–10 dGH while Green Spotted Puffer (Brackish) requires 12–30 dGH.
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. An aquarium test kit is recommended for monitoring.
Tank Setup
To house Gardner's Killifish and Green Spotted Puffer (Brackish) together, plan for an aquarium of at least 137 litres with a minimum length of 80 cm. This accounts for the larger species' space requirements with an additional 20 % buffer to reduce territorial tension.
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, Plants - lighly covered, 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.
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Frequently Asked Questions
Can Gardner's Killifish and Green Spotted 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 Gardner's Killifish and Green Spotted Puffer (Brackish) need?▾
A minimum of 137 litres (tank length at least 80 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 Gardner's Killifish and Green Spotted Puffer (Brackish) together?▾
Keep the aquarium between 24°C and 26°C. A target of around 25.0°C sits comfortably within both species' preferred ranges.
Are Gardner's Killifish or Green Spotted Puffer (Brackish) aggressive?▾
Gardner's Killifish is generally mild-mannered (4/10) and Green Spotted Puffer (Brackish) is highly aggressive (9/10). The gap in aggression levels means the calmer fish may experience stress from the more assertive one.
What pH do Gardner's Killifish and Green Spotted Puffer (Brackish) need?▾
Both species overlap in the 7.5–7.5 pH range. Consistency is key — avoid sudden swings, and test regularly to stay within this window.
Will Green Spotted Puffer (Brackish) nip Gardner's Killifish's fins?▾
Green Spotted Puffer (Brackish) is a known fin nipper. If Gardner's Killifish has long or flowing fins, there is a real risk of fin damage. Keeping Green Spotted Puffer (Brackish) in a larger group can help redirect nipping behaviour toward conspecifics.
How do I manage Green Spotted Puffer (Brackish)'s territorial behaviour?▾
Provide line-of-sight breaks using rocks, driftwood, and dense planting. A larger tank gives Green Spotted 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.
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