Can Harlequin Rasbora and Siamese Algae Eater Live Together?

Harlequin Rasbora is a peaceful species (1/10), while Siamese Algae Eater is generally mild-mannered (3/10). This modest difference means Siamese Algae Eater may occasionally assert dominance over Harlequin Rasbora.

Harlequin Rasbora and Siamese Algae Eater both frequent the 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: Siamese Algae Eater is a known jumper, so a tight-fitting lid is essential.

The safe temperature window for both species falls between 22°C and 28°C. Aim for the midpoint of this range (around 25.0°C) for optimal comfort.

Both fish can tolerate a pH between 6 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 5–12 dGH. Regular testing will ensure conditions stay within this range.

To house Harlequin Rasbora and Siamese Algae Eater together, plan for an aquarium of at least 132 litres with a minimum length of 90 cm. This accounts for the larger species' space requirements with an additional 20 % buffer to reduce territorial tension.

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, Leaf Litter/Blackwater, Established Algae (Otocinclus), Driftwood (Digestion/Hiding), Plants - lighly covered. Meeting these requirements will help both species thrive.

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