Can Chinese Algae Eater (CAE) and Red-Bellied Piranha Live Together?

Both Chinese Algae Eater (CAE) and Red-Bellied Piranha are semi-aggressive species with an aggression score of 8/10. Their matching temperaments mean neither fish is likely to dominate the other in a shared aquarium.

Both Chinese Algae Eater (CAE) and Red-Bellied Piranha are highly aggressive, increasing the risk of violent confrontations.

Chinese Algae Eater (CAE) and Red-Bellied Piranha 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.

There is a critical concern: the Slime Coat Eater (Attacks Flat Fish) behaviour of one fish directly conflicts with the Shy / Slow Moving (Easily Stressed) trait of the other — slime coat eaters target slow-moving fish, causing severe stress and health issues..

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. Two aggressive species housed together increases risk of fighting.

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 6 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 5–15 dGH. Regular testing will ensure conditions stay within this range.

To house Chinese Algae Eater (CAE) and Red-Bellied Piranha together, plan for an aquarium of at least 413 litres with a minimum length of 120 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), Driftwood (Digestion/Hiding), Plants - Floating. Meeting these requirements will help both species thrive.

Both species do well with high (river/stream) water movement, so a standard filtration setup rated for the tank volume should suffice.

Chinese Algae Eater (CAE) and Red-Bellied Piranha 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.