Can Aequidens diadema (Diadem Cichlid) and Flagtail Prochilodus Live Together?

Both Aequidens diadema (Diadem Cichlid) and Flagtail Prochilodus are moderately assertive species with an aggression score of 6/10. Their matching temperaments mean neither fish is likely to dominate the other in a shared aquarium.

Aequidens diadema (Diadem Cichlid) and Flagtail Prochilodus 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.

Worth noting: Flagtail Prochilodus is a known jumper, so a tight-fitting lid is essential.

To improve the chances of a peaceful coexistence in this community tank: Provide a significantly larger tank (at least 50% more volume than the minimum) to allow both Aequidens diadema (Diadem Cichlid) and Flagtail Prochilodus to establish separate territories. Add plenty of line-of-sight breaks using driftwood, rocks, and dense planting to reduce territorial confrontations.

The safe temperature window for both species falls between 23°C and 28°C. Aim for the midpoint of this range (around 25.5°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 Aequidens diadema (Diadem Cichlid) and Flagtail Prochilodus together, plan for an aquarium of at least 500 litres with a minimum length of 150 cm. This recommendation combines the stricter species minimums with a community-load allowance so the pairing has realistic long-term space and filtration headroom.

Because this pairing requires extra vigilance, include plenty of hiding spots — caves, driftwood, and dense plant clusters — so the less dominant fish can retreat when needed.

Specific environmental needs for this combination include: Sand (Sifters), Driftwood (Digestion/Hiding), Established Algae (Otocinclus). Meeting these requirements will help both species thrive.

Aequidens diadema (Diadem Cichlid) prefers Low (Still Water) flow while Flagtail Prochilodus needs High (River/Stream) flow. Consider positioning filter outlets and using baffles to create zones of different current intensity within the same tank.