Can Allen's Rainbowfish and Cardinal Shrimp (Sulawesi) Live Together?

Allen's Rainbowfish is a peaceful species (2/10), while Cardinal Shrimp (Sulawesi) is peaceful (0/10). This modest difference means Allen's Rainbowfish may occasionally assert dominance over Cardinal Shrimp (Sulawesi).

In terms of spatial distribution, Allen's Rainbowfish prefers the Top (Surface) and Middle (Open Water) zones, whereas Cardinal Shrimp (Sulawesi) occupies the Bottom (Substrate) zone. 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: Allen's Rainbowfish is a known jumper, so a tight-fitting lid is essential.

To improve the chances of a peaceful coexistence in this community tank: A larger aquarium with ample hiding spots can help diffuse aggression and give the less dominant fish space to retreat.

The safe temperature window for both species falls between 26°C and 29°C. Aim for the midpoint of this range (around 27.5°C) for optimal comfort.

Both fish can tolerate a pH between 7.5 and 8.4. Maintaining a stable value within this band is more important than hitting an exact number.

For general hardness, the shared comfort zone is 4–8 dGH. Regular testing will ensure conditions stay within this range.

To house Allen's Rainbowfish and Cardinal Shrimp (Sulawesi) together, plan for an aquarium of at least 150 litres with a minimum length of 120 cm. This recommendation combines the stricter species minimums with a community-load allowance so the pairing has realistic long-term space and filtration headroom.

Because this pairing requires extra vigilance, include plenty of hiding spots — caves, driftwood, and dense plant clusters — so the less dominant fish can retreat when needed.

Specific environmental needs for this combination include: Plants - lighly covered, Driftwood (Digestion/Hiding), Established Algae (Otocinclus), Smooth Gravel (Sensitive Barbels), Sand (Sifters). 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.