Can Fiddler Crab (Brackish) and Senegal Bichir Live Together?

Fiddler Crab (Brackish) is a generally mild-mannered species (3/10), while Senegal Bichir is moderately assertive (6/10). This modest difference means Senegal Bichir may occasionally assert dominance over Fiddler Crab (Brackish).

Fiddler Crab (Brackish) and Senegal Bichir 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.

Worth noting: Senegal Bichir is nocturnal and will be most active after lights-out, naturally reducing daytime encounters. Also, Senegal Bichir is a known jumper, so a tight-fitting lid is essential.

The safe temperature window for both species falls between 25°C and 29°C. Aim for the midpoint of this range (around 27.0°C) for optimal comfort.

Both fish can tolerate a pH between 7.5 and 7.8. Maintaining a stable value within this band is more important than hitting an exact number.

For general hardness, the shared comfort zone is 10–20 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 Fiddler Crab (Brackish) and Senegal Bichir together, plan for an aquarium of at least 240 litres with a minimum length of 120 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), Driftwood (Digestion/Hiding), Smooth Gravel (Sensitive Barbels). 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.