Can Chao Phraya Giant Catfish (Paroon Shark) and Fiddler Crab (Brackish) Live Together?

Chao Phraya Giant Catfish (Paroon Shark) is a semi-aggressive species (8/10), while Fiddler Crab (Brackish) is generally mild-mannered (3/10). This notable difference means Chao Phraya Giant Catfish (Paroon Shark) may occasionally assert dominance over Fiddler Crab (Brackish).

Chao Phraya Giant Catfish (Paroon Shark) and Fiddler Crab (Brackish) 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: Chao Phraya Giant Catfish (Paroon Shark) is a known jumper, so a tight-fitting lid is essential.

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.

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.

To house Chao Phraya Giant Catfish (Paroon Shark) and Fiddler Crab (Brackish) together, plan for an aquarium of at least 15000 litres with a minimum length of 600 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: Smooth Gravel (Sensitive Barbels), Sand (Sifters), Driftwood (Digestion/Hiding). Meeting these requirements will help both species thrive.

Chao Phraya Giant Catfish (Paroon Shark) prefers High (River/Stream) flow while Fiddler Crab (Brackish) needs Low (Still Water) flow. Consider positioning filter outlets and using baffles to create zones of different current intensity within the same tank.

Chao Phraya Giant Catfish (Paroon Shark) and Fiddler Crab (Brackish) 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.