Can Australian Pearl Arowana and Masked Julie (Julidochromis) Live Together?

Australian Pearl Arowana is a highly aggressive species (9/10), while Masked Julie (Julidochromis) is moderately assertive (6/10). This modest difference means Australian Pearl Arowana may occasionally assert dominance over Masked Julie (Julidochromis).

In terms of spatial distribution, Australian Pearl Arowana prefers the Top (Surface) zone, whereas Masked Julie (Julidochromis) occupies the Bottom (Substrate) and Middle (Open Water) zones. Because they use different levels of the water column, territorial disputes are less likely and the tank will appear more balanced.

Additional behavioural considerations to keep in mind: Aggressive fish may bully and stress shy, slow-moving species. Two territorial species may clash over territory, especially in smaller tanks.

Worth noting: Australian Pearl Arowana is a known jumper, so a tight-fitting lid is essential.

The safe temperature window for both species falls between 24°C and 27°C. Aim for the midpoint of this range (around 25.5°C) for optimal comfort.

The pH requirements of Australian Pearl Arowana (6–7.5) and Masked Julie (Julidochromis) (8–9) do not overlap, making it impossible to satisfy both species simultaneously.

For general hardness, the shared comfort zone is 10–15 dGH. Regular testing will ensure conditions stay within this range.

To house Australian Pearl Arowana and Masked Julie (Julidochromis) together, plan for an aquarium of at least 800 litres with a minimum length of 200 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). Meeting these requirements will help both species thrive.

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

Australian Pearl Arowana and Masked Julie (Julidochromis) 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.