Actually, that is a very good question. So many people love the idea of at least once having a bunch of fry, and might not think much about what to do with them once they grow to a certain point. I guess it all depends on how much time, space, and yes, money you wonna invest in the whole thing.
If you really can't afford any more tanks (or the spouse looks crummy when you even mention it

), then its the best to either find them new homes with friends and other goldfish loving people ( the local club comes to mind here) or you give them to a fish store that you trust in taking good care of them.
Or if you are like me, a few extra fish don't really matter to me. I always dig up a tub or tank somewhere, and I have filters laying around whenever I'd need one. I have a bunch of 2 months old wakin fry right now, roughly 150 fish, they are at the 2 inch mark right now, give or take. I definetely just pick out the ones that aren't having wakin standards or a really ugly color, and give those to a very good pet store in town. The rest (which should be a huge number

) I keep and give them their own pond eventually. Wakin are very easy to breed, and the offspring has very little deformities, which is a good thing.