Nothingwhat eats them?
Nothingwhat kills them?
Interceptor is the most common treatment. It's a dog worming medicine available by prescription only. Your vet may help you out. Some do some don't. Mine didn't so I took my business elsewhere!and is it safe to use with fish and coral???
a dragon face pipe fish will eat them, but I don't recommend going out and getting one
http://www.liveaquaria.com/PIC/article.cfm?aid=31
Do a search for flatworms.