Can Altum Angel and Wels Catfish (European Catfish) Live Together?

Altum Angel is a moderately assertive species (5/10), while Wels Catfish (European Catfish) is semi-aggressive (8/10). This modest difference means Wels Catfish (European Catfish) may occasionally assert dominance over Altum Angel.

In terms of spatial distribution, Altum Angel prefers the Middle (Open Water) zone, whereas Wels Catfish (European Catfish) occupies the Bottom (Substrate) zone. 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: Wels Catfish (European Catfish) is nocturnal and will be most active after lights-out, naturally reducing daytime encounters.

There is no temperature overlap between Altum Angel (27–32°C) and Wels Catfish (European Catfish) (4–25°C). This fundamental mismatch makes long-term cohabitation impractical.

Both fish can tolerate a pH between 6 and 6.5. Maintaining a stable value within this band is more important than hitting an exact number.

For general hardness, the shared comfort zone is 5–5 dGH. Regular testing will ensure conditions stay within this range.

To house Altum Angel and Wels Catfish (European Catfish) together, plan for an aquarium of at least 10000 litres with a minimum length of 400 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 - Floating, Smooth Gravel (Sensitive Barbels). 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.

Altum Angel and Wels Catfish (European Catfish) 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.