Can Figure 8 Puffer (Brackish) and Pygmy Corydoras Live Together?

Figure 8 Puffer (Brackish) is a semi-aggressive species (8/10), while Pygmy Corydoras is peaceful (0/10). This notable difference means Figure 8 Puffer (Brackish) may occasionally assert dominance over Pygmy Corydoras.

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

Figure 8 Puffer (Brackish) and Pygmy Corydoras both frequent the Middle (Open Water) and 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. Shrimp eaters may also prey on very small nano fish.

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.

For general hardness, the shared comfort zone is 10–15 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.

To house Figure 8 Puffer (Brackish) and Pygmy Corydoras 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), 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.

Feeding time deserves special attention with this pairing. Figure 8 Puffer (Brackish) is a known shrimp eater and may prey on small invertebrates or nano fish like Pygmy Corydoras.