(Why can't medicines be one or two syllables? "Zap!" worm cure.)

My impression is that the whole tank can be treated. Rocks and plants should be safe after the treatment.

I don't know how deep the gravel would be before it is untreated, but camellanus is usually transfered from infected to non-infected fish when the host fish dies and the other fish nibble at the body or previously at feces. It can go for generations in a tank this way. Livebearers are among those particularly vulnerable to this infestation.

In nature there is a copepod (a tiny crustacean)which is the secondary host. That doesn't seem to be necessary in an aquarium. I have a hunch that camellanus may exist for quite a while in the fish before they are noticed.

Scott and Red may be right, that internally the guppies are too messed up to reproduce, even after the worms are destroyed.

But you know what? In a week to two weeks the tank should be worm free. I'd wait another couple of weeks to see if there would be fry if the guppies were old friends. ;)

.....

In related news, an aquarist took two containers with a small number of blackworms. One was just placed in an aquarium. The identical container was placed with a similar number of worms in a tank treated with flubendazole. The treated worms were dead in four days. The control group were still kicking!

This experiment needs to be repeated. It does also suggest that if you have blackworms in your gravel, you may want to wash out the gravel or pull it (and boil it while you are treating the tank). Otherwise a lot of dead blackworms could really foul the aquarium!

If I were you I'd take most of the gravel out in a soup pot and - was this G.G. who suggested -leave the gravel in an over at 250 degrees over night?

I would begin treatment of the tank at the same time. I'd throw the siphon tube in the tank during the 1-2 week treatment too. ;)