My old oscar got along fine with my pleco. Oscar (original name, huh?) would tear apart just about anything (loved goldfish and crayfish) but he pretty much ignored my pleco.I got the oscar when he was really small (three inches) and the pleco was already 6. The pleco got to be fifteen inches before we brought him back to the store, and Oscar maxed out at about 13. They never had a problem with eachother, but I say if you get a pleco, make sure its at least as big as the oscar. If they grow up together, they get used to eachother. Oscar was also in with a bicher. The only problem was that the bicher never got any food because the oscar was quicker- quite an eating machine.