plecos and scaleless fish are generally not good together. the same warnings goes for bichirs and plecos. plecos apparently do not mix well with them cause of their slime coat and they are at the bottom so they are easy prey. my pleco is 18 inches and with 5 different bichirs and scaleless fish. I think as long as the pleco is fed well it should not be a problem. this is from my own experience. But your pleco may not be as nice as mine. and the problem with having the pleco constantly fed is that the amount of poop plecos make its 50x more than a normal fish.