lol, you dont get them to do anything, its called manhandling...
alot of people treat fish like delicate butterflys, they are pretty durably actually, if people treated their fish a little rougher when they just started to get ill, they would have alot better luck at treating them. By rougher i mean, grab your starving fishy, pry their mouth open and stuff them full of food, when they have ick or velvet, get out the soft bristle toothbrush and give them a vigirous scrub, when they have bloat, stab them with a real syringe and drain the air out(this takes a little more skill), if they have a bad parisite, cut it out, Ive cut out gill tissue and not had problems. Most people dont seem to treat their sick fish untill their fish is really sick, then its too late...