O.K., then - I'm not sure what's going on with the fish. In some cases, if a fish has a severe fluke infestation, the first dose of prazi causes all the flukes to drop off at once. The flukes had been acting like little "corks" and when they drop off, the fish literally bleeds out and can die. However, that issue is NOT seen in the second, or subsequent doses. I think the prazi is coincidental to some other, unknown issue with the wrasse. I wish I could tell you what that issue is, but I'm just not sure, other than it could be the general delicate nature of this species.
Jay