Once they feel comfortable in your tank, they'll eat their way through your plants within 48 hours.
Please note that Silver Dollars can not live of flake and will not accept any meaty foods at all. You will Have to feed them lettuce, spinach and other green foods on a daily base.
My silver dollars obviously didnt read the handbook then as they demolish any meaty foods they can steal off the predators they share a tank with, even if veggies are in the tank (as they are daily) they will stop nibbling on them and make a dash to get at the frozen fish, mussels or whatever meaty frozen food i'm serving up that night. Some sources state that wild silver dollars will hunt down and eat very small fish so prehaps they arent the peacefull vegetarians that everyone thinks they are?