How to rehome fish when you don't know any other fish keepers?
Try your lfs, even the big boxes may take fish. Otherwise, classified ads on places like your regional equivalent of Craigslist or if you're up to shipping, there's ebay, aquabid, or the classified section here, once you have enough of a posting history.
You could post on Craigslist or similar sites. Chances are you will get an offer quickly, especially if it's free.
I had the same problem a few years again. Normally if you call a LFS and say you will donate the fish, they will gladly take it. If you ask for money, they will most likely say no. Just speaking from experience.