Can Beckford's Pencilfish and Chinese Algae Eater (CAE) Live Together?

Beckford's Pencilfish is a peaceful species (2/10), while Chinese Algae Eater (CAE) is semi-aggressive (8/10). This notable difference means Chinese Algae Eater (CAE) may occasionally assert dominance over Beckford's Pencilfish.

Large aggression gap (6 points) between Beckford's Pencilfish and Chinese Algae Eater (CAE) increases stress risk for the more peaceful fish.

In terms of spatial distribution, Beckford's Pencilfish prefers the Top (Surface) and Middle (Open Water) zones, whereas Chinese Algae Eater (CAE) 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.

There is a critical concern: the Shy / Slow Moving (Easily Stressed) behaviour of one fish directly conflicts with the Slime Coat Eater (Attacks Flat Fish) 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: Beckford's 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 7.5. Maintaining a stable value within this band is more important than hitting an exact number.

For general hardness, the shared comfort zone is 5–15 dGH. Regular testing will ensure conditions stay within this range.

To house Beckford's Pencilfish and Chinese Algae Eater (CAE) 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: Plants - Densely covered, Plants - Floating, Leaf Litter/Blackwater, Smooth Gravel (Sensitive Barbels). Meeting these requirements will help both species thrive.

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

Beckford's Pencilfish and Chinese Algae Eater (CAE) 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.