I have 5 Tapajos in with three gold fish(9"ea.), 1 Koi(9"), 1 Royal Pleco(10"), 1 Sailfin Pleco(15"), 1 Oscar(15"), 2 Geophagus Leucostica(8+"), 2 Geophagus Daemon(8"), 1 Blue Botia Loach(8"), and 2 green Bay Snooks(9").
Everytone gets along but the Oscar doesnt like anyone in his territory. For now all is well but it could change...the point is to be vigilant and watch the fish as they grow and mature.