Can Figure 8 Puffer (Brackish) and Redline Rasbora Live Together?

Figure 8 Puffer (Brackish) is a semi-aggressive species (8/10), while Redline Rasbora is peaceful (1/10). This notable difference means Figure 8 Puffer (Brackish) may occasionally assert dominance over Redline Rasbora.

Large aggression gap (7 points) between Figure 8 Puffer (Brackish) and Redline Rasbora increases stress risk for the more peaceful fish.

Figure 8 Puffer (Brackish) and Redline Rasbora 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.

Worth noting: Redline Rasbora is a known jumper, so a tight-fitting lid is essential.

The safe temperature window for both species falls between 24°C and 27°C. Aim for the midpoint of this range (around 25.5°C) for optimal comfort.

The pH requirements of Figure 8 Puffer (Brackish) (7.5–8.5) and Redline Rasbora (4–6.8) do not overlap, making it impossible to satisfy both species simultaneously.

Hardness requirements are incompatible: Figure 8 Puffer (Brackish) needs 10–25 dGH while Redline Rasbora requires 1–8 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.

To house Figure 8 Puffer (Brackish) and Redline Rasbora together, plan for an aquarium of at least 80 litres with a minimum length of 80 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), Leaf Litter/Blackwater, Driftwood (Digestion/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.

Figure 8 Puffer (Brackish) and Redline Rasbora 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.