Can Chinese Algae Eater (CAE) and Dwarf Pencilfish Live Together?

Chinese Algae Eater (CAE) is a semi-aggressive species (8/10), while Dwarf Pencilfish is peaceful (1/10). This notable difference means Chinese Algae Eater (CAE) may occasionally assert dominance over Dwarf Pencilfish.

Large aggression gap (7 points) between Chinese Algae Eater (CAE) and Dwarf Pencilfish increases stress risk for the more peaceful fish.

In terms of spatial distribution, Chinese Algae Eater (CAE) prefers the Bottom (Substrate) zone, whereas Dwarf Pencilfish 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.

There is a critical concern: the Slime Coat Eater (Attacks Flat Fish) behaviour of one fish directly conflicts with the Shy / Slow Moving (Easily Stressed) trait of the other — slime coat eaters target slow-moving fish, causing severe stress and health issues..

Additional behavioural considerations to keep in mind: Aggressive fish may bully and stress shy, slow-moving species. Hyperactive swimmers can stress shy, slow-moving species through constant motion.

Worth noting: Dwarf Pencilfish 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. Maintaining a stable value within this band is more important than hitting an exact number.

For general hardness, the shared comfort zone is 5–10 dGH. Regular testing will ensure conditions stay within this range.

To house Chinese Algae Eater (CAE) and Dwarf Pencilfish together, plan for an aquarium of at least 200 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.

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: Smooth Gravel (Sensitive Barbels), Plants - Densely covered, Plants - Floating, Leaf Litter/Blackwater. Meeting these requirements will help both species thrive.

Chinese Algae Eater (CAE) prefers High (River/Stream) flow while Dwarf Pencilfish needs Low (Still Water) flow. Consider positioning filter outlets and using baffles to create zones of different current intensity within the same tank.

Chinese Algae Eater (CAE) and Dwarf Pencilfish 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.