Mine definitely prefers being the only pleco in the tank. Had a rubberlip pleco for about five months, and once it settled and got a bit full of itself, they would chase one another, and the bristlenose would spend more time hiding. The rubberlip died in early October, and the Ancistrus has gone back to her perky self. She couldn't care less about corys or raphaels, but doesn't seem to like conspecifics. On the pleco Facebook group, I'm baffled by people's photos of multiple pleco species sharing courgettes like a loricariid commune. How do you get them to do that and not try to kill each other?