Can Aequidens sp. Atabapo and Molly (Sailfin/Black/Dalmatian) Live Together?

Aequidens sp. Atabapo is a moderately assertive species (6/10), while Molly (Sailfin/Black/Dalmatian) is generally mild-mannered (3/10). This modest difference means Aequidens sp. Atabapo may occasionally assert dominance over Molly (Sailfin/Black/Dalmatian).

Aequidens sp. Atabapo and Molly (Sailfin/Black/Dalmatian) both frequent the Middle (Open Water) region of the setup. This overlap can increase competition for space, so providing ample room and cover is important to keep both species comfortable.

The safe temperature window for both species falls between 25°C and 28°C. Aim for the midpoint of this range (around 26.5°C) for optimal comfort.

The pH requirements of Aequidens sp. Atabapo (4.5–7) and Molly (Sailfin/Black/Dalmatian) (7.5–8.5) do not overlap, making it impossible to satisfy both species simultaneously.

Hardness requirements are incompatible: Aequidens sp. Atabapo needs 1–8 dGH while Molly (Sailfin/Black/Dalmatian) requires 12–30 dGH.

To house Aequidens sp. Atabapo and Molly (Sailfin/Black/Dalmatian) together, plan for an aquarium of at least 110 litres with a minimum length of 90 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, Plants - Densely covered, Established Algae (Otocinclus). Meeting these requirements will help both species thrive.

Note a potential conflict in setup requirements: Aequidens sp. Atabapo is a plant destroyer, which conflicts with Molly (Sailfin/Black/Dalmatian)'s requirement for live plants. Compromise where possible or prioritise the more critical need.

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

Aequidens sp. Atabapo and Molly (Sailfin/Black/Dalmatian) 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.