Can Dusky Millions Fish and Loricaria spinulifera Live Together?

Dusky Millions Fish is a peaceful species (2/10), while Loricaria spinulifera is peaceful (1/10). This modest difference means Dusky Millions Fish may occasionally assert dominance over Loricaria spinulifera.

In terms of spatial distribution, Dusky Millions Fish prefers the Top (Surface) and Middle (Open Water) zones, whereas Loricaria spinulifera 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: Loricaria spinulifera 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 Loricaria spinulifera (25–29°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 Loricaria spinulifera 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: Plants - Densely covered, Plants - Floating, Established Algae (Otocinclus), Sand (Sifters), Driftwood (Digestion/Hiding), 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.

Dusky Millions Fish and Loricaria spinulifera 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.