Bala sharks need a 125 gallon minnimum and a group of 3 min. Clown loaches will eventualy require a 90 gallon and again, should be in a group of 3 at least. Zebra plecs aren't good at competeing for food but otherwise would be suitable though sometimes fragile. Flying foxes are great too, very active and will eat algae but they don't like others of their own kind so either keep a single one (prefferably) or a big group to spread out aggression (at least 6). Silver dollars would work just about but they are schooling fish so you should get at least 6 and they will decimate any plants. Basically, out of the fish you mentioned silver dollars, zebra plecs or a flying fox could work. Honestly, if you want zebra plecs, make it a peaceful planted community and a flying fox could go in as well. If you want silver dollars, make a tank especialy for them - maybe some kind of catfish as well - and don't include any real plants.
edit: spelling