I currently have 2 silver dollors in a 75gal that do fine for the last 4 years along with 2 blood parrots,4 hachlets,1 keyhole cichlid,2 glass cats; 6 diamond tretras,1 upside down fish and 1 bristle nose pleco,12 rainbow
I've personally tried Silver Dollars with Angels in a 55 and it didn't work out too well. The Silver Dollars are fast and boisterous. They also scare easy, which would then startle the Angels. Also, some of my Angels ended up with nipped ventral fins. I never determined if that was due to the SD's or the Pictus Cat though as I removed both species at the same time. My SD's are now happily residing as the dither fish in my 125 gal South American cichlid tank. They seem much happier.