Fenbendazole(Panacur) can have adverse effect on certain species of aquarium fish when dissolved in water.
I think what one uses all depends on what fish and other critters are in the tank.
Kusuri Wormer plus(FLUbendazole) is very safe on any fish and it's effect on planaria is similar to that of Fenbendazole.
Flubendazole however, will kill the snails, at least in the doses I did... I am surprised that Fenbendazole does not kill snails...Perhaps, again, it's all about the dosage...
I was reading somewhere that the difference between a poison, toxin and a cure is in the dosage...