Pipzine(Piperazine) is also recommended for treatment of nematodes but not cestodes. This is all guess work of course, but personally I would still try the metronidazole first. One reason is that most species of parasitic worms require intermediate hosts and cannot simply pass from one fish to another. We almost never deal with these things in the fish hobby but they are very common problems in dealing with reptiles -my other hobby. When I recieve new imported reptiles I give them metronidazole first then panacur. Typically flagellate infections will cause the animals to decline much more rapidly than worms which is why I use metronidazole first. This is why I try to order mostly captive bred reptiles - hence the name CB Pets.

Just to confuse things more, one intermediate host for some of the worms that affect fish are crustaceans. Do you feed your puffers and triggers "FRESH" HEB shrimp?