Just heard back from my LFS, and he's had no issues using CP on fairy
or flasher wrasses. But he does report problems using it on Six Line and some
Halichoeres genus wrasses (exs. Melanurus, Yellow Coris). However, I will make it a point to test CP on more flasher wrasses in the future so we can get to the bottom of this. In the meantime, I'm going to change the CP sticky to recommend
not using CP on any wrasses for the time being. There's just too much confusion regarding this issue right now. Wrasses seem to handle chelated copper well anyway, so that is probably the best chemical option for them.
@DrCooper I noticed you said you were using "General Cure, Furan 2 and Kanaplex" with CP. While I have mixed all those before, it's probably not optimal to do so. In the future I would omit the antibiotics (Furan 2 and Kanaplex) unless you are seeing symptoms of a bacterial disease. Those two are the worst when it comes to appetite suppression and oxygen depletion. Not saying for sure this is your problem, but it's worth mentioning as a possibility. In any case, I am very sorry to hear about the loss of your wrasses.