Can Freshwater Harlequin Shrimp (Sulawesi) and Lake Wanam Rainbowfish Live Together?

Freshwater Harlequin Shrimp (Sulawesi) is a peaceful species (0/10), while Lake Wanam Rainbowfish is peaceful (2/10). This modest difference means Lake Wanam Rainbowfish may occasionally assert dominance over Freshwater Harlequin Shrimp (Sulawesi).

In terms of spatial distribution, Freshwater Harlequin Shrimp (Sulawesi) prefers the Bottom (Substrate) zone, whereas Lake Wanam Rainbowfish 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.

Worth noting: Freshwater Harlequin Shrimp (Sulawesi) is nocturnal and will be most active after lights-out, naturally reducing daytime encounters. Also, Lake Wanam Rainbowfish is a known jumper, so a tight-fitting lid is essential.

The safe temperature window for both species falls between 26°C and 30°C. Aim for the midpoint of this range (around 28.0°C) for optimal comfort.

Both fish can tolerate a pH between 7.5 and 8.5. Maintaining a stable value within this band is more important than hitting an exact number.

Hardness requirements are incompatible: Freshwater Harlequin Shrimp (Sulawesi) needs 4–8 dGH while Lake Wanam Rainbowfish requires 10–20 dGH.

To house Freshwater Harlequin Shrimp (Sulawesi) and Lake Wanam Rainbowfish 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: Established Algae (Otocinclus), Smooth Gravel (Sensitive Barbels), Plants - Densely covered. 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.

Freshwater Harlequin Shrimp (Sulawesi) and Lake Wanam Rainbowfish 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.