Can Chocolate Gourami and Dusky Millions Fish Live Together?

Both Chocolate Gourami and Dusky Millions Fish are peaceful species with an aggression score of 2/10. Their matching temperaments mean neither fish is likely to dominate the other in a shared aquarium.

Chocolate Gourami and Dusky Millions Fish both frequent the Top (Surface) and 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.

Additional behavioural considerations to keep in mind: Hyperactive swimmers can stress shy, slow-moving species through constant motion.

There is no temperature overlap between Chocolate Gourami (25–30°C) and Dusky Millions Fish (16–24°C). This fundamental mismatch makes long-term cohabitation impractical.

The pH requirements of Chocolate Gourami (4–6.5) and Dusky Millions Fish (7–8) do not overlap, making it impossible to satisfy both species simultaneously.

Hardness requirements are incompatible: Chocolate Gourami needs 0–5 dGH while Dusky Millions Fish requires 8–20 dGH.

To house Chocolate Gourami and Dusky Millions Fish together, plan for an aquarium of at least 55 litres with a minimum length of 60 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: Leaf Litter/Blackwater, Plants - Densely covered, Plants - Floating, Driftwood (Digestion/Hiding), Established Algae (Otocinclus). Meeting these requirements will help both species thrive.

Note a potential conflict in setup requirements: Dusky Millions Fish is a plant destroyer, which conflicts with Chocolate Gourami'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.

Chocolate Gourami and Dusky Millions Fish 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.