I have a 9" Pleco in my tank w/ about a dozen Africans of different types and one Jack Dempsey. Every now and then they all tend to get annoyed by the Pleco. The funniest thing I have seen though is one night when the Pleco was attached about halfway up the front of the tank, my M. Auratus would swim to the bottom of the tank, pick up some gravel, and then swim to the top of the tank and drop it on the Pleco. He did this about 20-25 times with out taking a break. I have never seen anything like it.