Can Royal Pleco (L190) and Siamese Algae Eater Live Together?

Royal Pleco (L190) is a moderately assertive species (5/10), while Siamese Algae Eater is generally mild-mannered (3/10). This modest difference means Royal Pleco (L190) may occasionally assert dominance over Siamese Algae Eater.

Royal Pleco (L190) and Siamese Algae Eater 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.

Additional behavioural considerations to keep in mind: Two territorial species may clash over territory, especially in smaller tanks.

Worth noting: Royal Pleco (L190) is nocturnal and will be most active after lights-out, naturally reducing daytime encounters. Also, Siamese Algae Eater is a known jumper, so a tight-fitting lid is essential.

To improve the chances of a peaceful coexistence in this community tank: Provide a significantly larger tank (at least 50% more volume than the minimum) to allow both Royal Pleco (L190) and Siamese Algae Eater to establish separate territories. Add plenty of line-of-sight breaks using driftwood, rocks, and dense planting to reduce territorial confrontations.

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 6.5 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. An aquarium test kit is recommended for monitoring.

To house Royal Pleco (L190) and Siamese Algae Eater together, plan for an aquarium of at least 540 litres with a minimum length of 150 cm. This accounts for the larger species' space requirements with an additional 20 % buffer to reduce territorial tension.

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: Driftwood (Digestion/Hiding), Established Algae (Otocinclus), Plants - lighly covered. Meeting these requirements will help both species thrive.

Note a potential conflict in setup requirements: Royal Pleco (L190) is a plant destroyer, which conflicts with Siamese Algae Eater's requirement for live plants. Compromise where possible or prioritise the more critical need.

Both species do well with high (river/stream) water movement, so a standard filtration setup rated for the tank volume should suffice.