Can Cardinal Shrimp (Sulawesi) and Dusky Millions Fish Live Together?

Cardinal Shrimp (Sulawesi) is a peaceful species (0/10), while Dusky Millions Fish is peaceful (2/10). This modest difference means Dusky Millions Fish may occasionally assert dominance over Cardinal Shrimp (Sulawesi).

In terms of spatial distribution, Cardinal Shrimp (Sulawesi) prefers the Bottom (Substrate) zone, whereas Dusky Millions Fish 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.

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

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

Both fish can tolerate a pH between 7.5 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 8–8 dGH. Regular testing will ensure conditions stay within this range.

To house Cardinal Shrimp (Sulawesi) and Dusky Millions Fish together, plan for an aquarium of at least 41 litres with a minimum length of 45 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: Established Algae (Otocinclus), Smooth Gravel (Sensitive Barbels), Sand (Sifters), 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.

Cardinal Shrimp (Sulawesi) 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.