Can Assassin Snail and Copper Harlequin Rasbora Live Together?

Assassin Snail is a peaceful species (2/10), while Copper Harlequin Rasbora is peaceful (1/10). This modest difference means Assassin Snail may occasionally assert dominance over Copper Harlequin Rasbora.

In terms of spatial distribution, Assassin Snail prefers the Bottom (Substrate) zone, whereas Copper Harlequin Rasbora 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.

Worth noting: Copper Harlequin Rasbora is a known jumper, so a tight-fitting lid is essential.

The safe temperature window for both species falls between 23°C and 28°C. Aim for the midpoint of this range (around 25.5°C) for optimal comfort.

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 8–10 dGH. Regular testing will ensure conditions stay within this range.

To house Assassin Snail and Copper Harlequin Rasbora together, plan for an aquarium of at least 38 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: Sand (Sifters), Plants - Densely covered, Plants - Floating, Leaf Litter/Blackwater. 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.