Can Delicate Blue-Eye and Dusky Millions Fish Live Together?

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

Delicate Blue-Eye 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.

Worth noting: Delicate Blue-Eye is a known jumper, so a tight-fitting lid is essential.

There is no temperature overlap between Delicate Blue-Eye (25–32°C) and Dusky Millions Fish (16–24°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 8–15 dGH. Regular testing will ensure conditions stay within this range.

To house Delicate Blue-Eye and Dusky Millions Fish together, plan for an aquarium of at least 60 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: Plants - Densely covered, Plants - Floating, 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 Delicate Blue-Eye's requirement for live plants. Compromise where possible or prioritise the more critical need.

Both species do well with moderate (standard) water movement, so a standard filtration setup rated for the tank volume should suffice.

Delicate Blue-Eye 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.