So I took down the QT tank a day after putting it up. Gave up on ever catching Snaky Fish, and was advised on the forum that I ought to treat the main tank anyway. Sigh. Well, the good of it is now I have a decent QT if I ever really need it (using meds that would kill the snail population or newcomers). I was annoyed with myself at having taken the trouble to set it up, and then tearing it all down again.
So now I am dosing meds in the main tank. Gave the first one on tuesday and today is second dose of Metronidazole. I have not noticed anything different with the kuhlis- except that they seem very happy to be all back in the home tank together. I don't see them pooping out any dead worms, although maybe that only occurs with the other meds I have yet to give them. One thing is sure- Snaky Fish was a lot more active going after food today, so maybe he is feeling better.