Can Apistogramma atahualpa and Vieja fenestrata Live Together?

Apistogramma atahualpa is a generally mild-mannered species (4/10), while Vieja fenestrata is semi-aggressive (8/10). This notable difference means Vieja fenestrata may occasionally assert dominance over Apistogramma atahualpa.

Apistogramma atahualpa and Vieja fenestrata 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.

Additional behavioural considerations to keep in mind: Two territorial species may clash over territory, especially in smaller tanks.

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.

The pH requirements of Apistogramma atahualpa (4.5–6.5) and Vieja fenestrata (7–8) do not overlap, making it impossible to satisfy both species simultaneously.

Hardness requirements are incompatible: Apistogramma atahualpa needs 0–5 dGH while Vieja fenestrata requires 8–20 dGH.

To house Apistogramma atahualpa and Vieja fenestrata together, plan for an aquarium of at least 450 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.

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), Leaf Litter/Blackwater, Driftwood (Digestion/Hiding), Plants - Densely covered, Smooth Gravel (Sensitive Barbels). Meeting these requirements will help both species thrive.

Note a potential conflict in setup requirements: Vieja fenestrata is a plant destroyer, which conflicts with Apistogramma atahualpa'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.

Apistogramma atahualpa and Vieja fenestrata 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.