That all depends on how often you feed, how often you water change. Power feeding is what you are after. 2-3 times a day, small amounts and lots of water changes. 2 x 50 percent every week. But competition for food will hold them down and slow them getting to 5 inch size if there are 40 silver dollars? Did I read that correct?
Hey al, are your silverdollars tankraised or wildcaught? Just curious, I bought 2 wild caught amazon orange fin silverdollars about 6-7'' and I love em.