You won't be able to get either by itself without a vet prescription, which is quite difficult to obtain. That being said, Jungle Medicated anti-parasite food contains one of the two meds you want. Petsmart carries a reptile pellet that is fish safe that also contains levamisole. Safeguard4 is a dog dewormer that contains fenbendazole. It can be used on fish too. Both levamisole and fenbendazole fall out of solution easily, so mixing with food is the best treatment. Angels Plus (website) carries a flake food medicated with fenbendazole. Unless you are convinced that your fish have camilanus worms, I would start with API General Cure. It contains both metronidozole and Praziquantinel.
