Can Chinese Algae Eater (CAE) and Least Killifish (Heterandria) Live Together?

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

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

Chinese Algae Eater (CAE) and Least Killifish (Heterandria) both frequent the Bottom (Substrate) region of the setup. This overlap can increase competition for space, so providing ample room and cover is important to keep both species comfortable.

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.

The safe temperature window for both species falls between 22°C and 27°C. Aim for the midpoint of this range (around 24.5°C) for optimal comfort.

Both fish can tolerate a pH between 7 and 8. 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. An aquarium test kit is recommended for monitoring.

To house Chinese Algae Eater (CAE) and Least Killifish (Heterandria) together, plan for an aquarium of at least 240 litres with a minimum length of 120 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: Smooth Gravel (Sensitive Barbels), Plants - Densely covered, Plants - Floating. Meeting these requirements will help both species thrive.

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