I kept an Argentea, Pearsei, and Blackbelt with my midas and had no issue. Also were 5 silver dollars and a pleco in the tank.
At times I tried different tankmates and never had an issue because my midas was ultra peaceful. He has had a Jack Dempsey, freddie, fenestratus, and convict in the mix at some point. This was in a 210g filltered with two FX5's.