Hi,
If you get the fenbendazole... DO NOT add it to the tank water..its got to be added to food. IF added to the water directly, it can kill fish.
To figure out the appropriate dose.....You'll need to know the concentration of the product you'll be getting.
hth,
-al
ps... The guys over at Bidka may be able to help you locate a good dewormer...
http://www.bidka.org/