I went back through my records and apparently one time I successfully treated a Quoyi with Chloroquine. But the medication was bleaching the coralline encrusted rocks I was putting in the QT to entice the Quoyi to eat, so I switched over to copper with the next one. I was so impressed with how unfazed that Quoyi (and other Parrotfish) seemed to be in copper that I started treating parrots exclusively with chelated copper.