Can Dusky Millions Fish and Peppermint Pleco Live Together?

Dusky Millions Fish is a peaceful species (2/10), while Peppermint Pleco is generally mild-mannered (3/10). This modest difference means Peppermint Pleco may occasionally assert dominance over Dusky Millions Fish.

In terms of spatial distribution, Dusky Millions Fish prefers the Top (Surface) and Middle (Open Water) zones, whereas Peppermint Pleco 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: Hyperactive swimmers can stress shy, slow-moving species through constant motion.

Worth noting: Peppermint Pleco is nocturnal and will be most active after lights-out, naturally reducing daytime encounters.

There is no temperature overlap between Dusky Millions Fish (16–24°C) and Peppermint Pleco (26–30°C). This fundamental mismatch makes long-term cohabitation impractical.

Both fish can tolerate a pH between 7 and 7.5. Maintaining a stable value within this band is more important than hitting an exact number.

For general hardness, the shared comfort zone is 8–12 dGH. Regular testing will ensure conditions stay within this range.

To house Dusky Millions Fish and Peppermint Pleco together, plan for an aquarium of at least 150 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: Plants - Densely covered, Plants - Floating, Established Algae (Otocinclus), Driftwood (Digestion/Hiding), Smooth Gravel (Sensitive Barbels). Meeting these requirements will help both species thrive.

Dusky Millions Fish prefers Low (Still Water) flow while Peppermint Pleco needs High (River/Stream) flow. Consider positioning filter outlets and using baffles to create zones of different current intensity within the same tank.

Dusky Millions Fish and Peppermint Pleco 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.