Can Wels Catfish (European Catfish) and White Cloud Mountain Minnow Live Together?

Wels Catfish (European Catfish) is a semi-aggressive species (8/10), while White Cloud Mountain Minnow is peaceful (1/10). This notable difference means Wels Catfish (European Catfish) may occasionally assert dominance over White Cloud Mountain Minnow.

Large aggression gap (7 points) between Wels Catfish (European Catfish) and White Cloud Mountain Minnow increases stress risk for the more peaceful fish.

In terms of spatial distribution, Wels Catfish (European Catfish) prefers the Bottom (Substrate) zone, whereas White Cloud Mountain Minnow occupies the Top (Surface) 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.

There is a critical concern: the Piscivore (Eats small/nano fish) behaviour of one fish directly conflicts with the Nano / Bite-sized (Predation Risk) trait of the other — piscivorous fish will prey on nano-sized tank mates..

Worth noting: Wels Catfish (European Catfish) is nocturnal and will be most active after lights-out, naturally reducing daytime encounters. Also, White Cloud Mountain Minnow is a known jumper, so a tight-fitting lid is essential.

The safe temperature window for both species falls between 14°C and 22°C. Aim for the midpoint of this range (around 18.0°C) for optimal comfort.

Both fish can tolerate a pH between 6 and 8. Maintaining a stable value within this band is more important than hitting an exact number.

For general hardness, the shared comfort zone is 5–20 dGH. Regular testing will ensure conditions stay within this range.

To house Wels Catfish (European Catfish) and White Cloud Mountain Minnow 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: Smooth Gravel (Sensitive Barbels), Driftwood (Digestion/Hiding), Plants - Densely covered. 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.

Wels Catfish (European Catfish) and White Cloud Mountain Minnow 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.