Hi,
Discomed or Pipzine (both have piperazine) are said to work.
IMO Flubendazole works best. Order it at http://www.4fishstuff.com/index.htm (download the catalog)
I don't care for Discoworm (too harsh)
Fluke tabs are suppose to work (some use at 1/2 strength)
hth
Ardan