Maybe a Jack Dempsey, Firemouth or a Parrot Cichlid? I think a Festivum should be fine also.
BTW Is that a Common Pleco? If so, I would recommend re-homing him, they can get big.
Someone correct me if i'm wrong though.
You may want to check the South/Central American Cichlid forum, just to be sure. IMO you are pretty well stocked at the moment.