Can Figure 8 Puffer (Brackish) and Kuhli Loach Live Together?
Figure 8 Puffer (Brackish) and Kuhli Loach 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
Behaviour & Temperament
Figure 8 Puffer (Brackish) is a semi-aggressive species (8/10), while Kuhli Loach is peaceful (0/10). This notable difference means Figure 8 Puffer (Brackish) may occasionally assert dominance over Kuhli Loach.
Large aggression gap (8 points) between Figure 8 Puffer (Brackish) and Kuhli Loach increases stress risk for the more peaceful fish.
Figure 8 Puffer (Brackish) and Kuhli Loach both frequent the Bottom (Substrate) 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.
Worth noting: Kuhli Loach is nocturnal and will be most active after lights-out, naturally reducing daytime encounters. Also, Kuhli Loach 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 Figure 8 Puffer (Brackish) (7.5–8.5) and Kuhli Loach (5.5–7) 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. An aquarium test kit is recommended for monitoring.
Tank Setup
To house Figure 8 Puffer (Brackish) and Kuhli Loach together, plan for an aquarium of at least 72 litres with a minimum length of 60 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: Sand (Sifters), Shells (Breeding/Hiding), Leaf Litter/Blackwater, Smooth Gravel (Sensitive Barbels), Plants - Densely covered. 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.
Find the right tank equipment
Browse tanks, décor, and equipment suited for this setup.
Frequently Asked Questions
Can Figure 8 Puffer (Brackish) and Kuhli Loach 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 Kuhli Loach need?▾
A minimum of 72 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 Figure 8 Puffer (Brackish) and Kuhli Loach 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 Kuhli Loach aggressive?▾
Figure 8 Puffer (Brackish) is semi-aggressive (8/10) and Kuhli Loach is peaceful (0/10). 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 Kuhli Loach need?▾
Their pH requirements do not overlap. Figure 8 Puffer (Brackish) prefers 7.5–8.5, while Kuhli Loach needs 5.5–7. This makes them incompatible in the same water chemistry.
Will Figure 8 Puffer (Brackish) nip Kuhli Loach's fins?▾
Figure 8 Puffer (Brackish) is a known fin nipper. If Kuhli Loach 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.
Does Kuhli Loach being nocturnal affect compatibility?▾
Kuhli Loach is most active after lights-out, which naturally reduces daytime encounters with its tank mate. This can actually be beneficial, as both fish get undisturbed time to feed and explore. Just ensure food reaches Kuhli Loach during evening hours.
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