CeeGee, its hard to say what it could be. I've had wrasses in the past have the same ailment. Likely an internal parasite or worm. The fish eats well but internally it's not getting the nutrition it needs. In most cases it dies of starvation. Don't mean to bum you out. But I recommend you try the forum boards (Fish Disease treatment) to try and have the experts pinpoint the cause. Then you may need to start treatment with a specific medicine.
Maracyn is good in that it provides many vitamins that the fish might not be getting with regular food consumption....or even spark up an appetite if the fish is not eating. Outside of fixing scratches, torn fins and popeye I view Maracyn as an IV for sick fish. When treated in a QT tank the fish has no choice but to drink in the Maracyn because it's diluted in the water.
As far as cyanide goes, it all depends on the collectors. There are many collectors. Some do the right thing and use only hand/net collecting techniques. Others take the stupid short cuts like cyanide, which harm much more than just the fish. As if we already didn't have enough problems with global warming affecting the reefs! There's no way to know if your fish was collected in this manner.
heuerfan, that may be a reason for the losses that you and your friend have had with the flames. But then again I don't know. It could be other illnesses like velvet in a bad or infected batch of fish. Just hard to say since I can't see the fish in person.