Generally peaceful but territorial from a young age. Some large specimens are aggressively territorial and may cause problems if housed with other large nocturnal fish.
The temptation with large tough Loricariids is to keep them with large, tough other fish such as Oscars or other brutish characters. This actually works quite well with most omnivorous or mainly vegetarian plecos. Pseudacanthicushowever are big messy carnivores, but, like all large plecos, produce vast amounts of waste and as such would require monumental filtration to house alongside non-catfish ”equals”. It is better to think of these catfish as the centrepiece fish and stock their aquarium with medium-sized (preferably omnivorous) fish. All sizes of barbs work surprisingly well.