i, like alot of ppl on here, have pctus and i think there great, and make fantastic oscar tank mates.
they do, as marcus says, need really good water conditions however. in theory they r nocternal but mine all seem very active during the day so

lol
good thing about them is they r aggressive feeders so can hold their own against oscars and other larger fish and make sure they get their fair share. i found with mine they rooted around in the gravel so muhc it uprooted some of my plants but thats all, in grand scheme of things not a big deal!
think they can grow up to 20cm but thats the very very max