Can Black Ocellatus and Glass Catfish Live Together?

Black Ocellatus is a semi-aggressive species (7/10), while Glass Catfish is peaceful (1/10). This notable difference means Black Ocellatus may occasionally assert dominance over Glass Catfish.

Large aggression gap (6 points) between Black Ocellatus and Glass Catfish increases stress risk for the more peaceful fish.

In terms of spatial distribution, Black Ocellatus prefers the Bottom (Substrate) zone, whereas Glass Catfish occupies the Middle (Open Water) zone. Because they use different levels of the water column, territorial disputes are less likely and the tank will appear more balanced.

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 Black Ocellatus (7.5–9) and Glass Catfish (6–7) do not overlap, making it impossible to satisfy both species simultaneously.

For general hardness, the shared comfort zone is 8–10 dGH. Regular testing will ensure conditions stay within this range.

To house Black Ocellatus and Glass Catfish 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), Shells (Breeding/Hiding), Plants - Densely covered, Plants - Floating. 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.

Black Ocellatus and Glass 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.