Can Discus and Regan's Julie Live Together?

Discus is a generally mild-mannered species (4/10), while Regan's Julie is semi-aggressive (7/10). This modest difference means Regan's Julie may occasionally assert dominance over Discus.

Discus and Regan's Julie 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: Two territorial species may clash over territory, especially in smaller tanks.

There is no temperature overlap between Discus (28–32°C) and Regan's Julie (23–27°C). This fundamental mismatch makes long-term cohabitation impractical.

The pH requirements of Discus (5–7.5) and Regan's Julie (8–9) do not overlap, making it impossible to satisfy both species simultaneously.

For general hardness, the shared comfort zone is 10–12 dGH. Regular testing will ensure conditions stay within this range.

To house Discus and Regan's Julie together, plan for an aquarium of at least 250 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: Sand (Sifters), Driftwood (Digestion/Hiding), Leaf Litter/Blackwater. 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.

Discus and Regan's Julie 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.