What I have said repeatedly is that we need more data about the water in this particular tank.

You and your husband were going by a slightly different set of instructions. You were using Lockwood's figures from his exploration of ratios for medication. I was going by Charles' 5 grams per 100 gallons or a gram per every 20 gallons. As a decidedly un-medical person, I simply don't know if the extra half a gram would make too much of a difference.

I notice in re-reading more of the conversations in http://www.guppylog.com/story/2006/4/29/164717/627
that Charles didn't go, in the case he alluded to, for a real long time. He treated for 36 hours, though he planned for 24 hours. He notes that when he re-treated those fish 2 weeks later, he stopped after only 20 hours "as it was VERY stressful on my fish".

Certainly that was still a huge time compared to the 30 awful minutes your fish endured.

So he has had difficulty in one situation too. I do know of other comments in programs where he recommends going a longer than the above case. He doesn't say why his fish were stressed, he just moved them out. So I guess we really need to watch them!

Could you try one obviously infected fish in a smaller container?

I've treated with three different anthelmintics, two in one commercial preparation in some cases. I didn't see the fish all that stressed. But I was treating new fish in a preventative mode (and if they expelled worms, they would probably have been smaller). The other treatments were with Praziquantel for anchor worms which infest gills when small and the fish's skin when large. As they were killed, they would just have fallen off.

Thank you for those water figures. I must have confused them with someone else's. (I owe you big time for that gaff.) Your tap certainly offers hard enough water for guppies. In fact you don't often want to top off evaporation with tap water and let it get continually harder.

And I have the testimony of a couple of people that after a point anthelmintics are hard to dissolve anyway. They vary by chemical.

Scott L's editorial introduction kind of indicated then that he felt that there was overdosing. Later he mentions that he would like to check with a friend at Shedd Aquarium and that he wonders if the issue was overdosing.

I may e-mail a URL of this discussion to Charles. His fish at least one time were awfully stressed too. Both of you removed your fish and their condition improved among the survivors.

If the cause of that wasn't over dosing, was the problem with the reaction of the internal worms and what it was doing to the fish? I don't really know what happened.

You asked about other treatments. For a while Flubendazole was preferred over Levamisole. Then it was unavailable for a time. I have purchased some of that from Charles. He has an ad and an article on that at the bottom of his home page. With the difficulty you have with having to get prescriptions through vets and the prices one must pay, I don't know if I should mention that.