I got a pair "used" from a woman's tank. They had a lot of fish to clean.
They also ate flake food. When I introduced nori to the tank, the wrasses were the first to take to it, then showed the tangs to eat it.
Then they jumped.
Since then, I have tried to find replacements.... I tried on 3 occasions. Once I picked one that was healthily cleaning other fish at the store. None made it though.
At the store, I have asked to see them fed to find one which takes to brine shrimp. In a tank full of cleaner wrasses, they *ALL* ignored the shrimp. I've never seen fish so completely disinterested in brine shrimp.
Tropical Paradise, the best LFS I know, won't carry them any more. They got sick of seeing them die, even in established tanks.
Another LFS got a big shipment of fish that I
saw. In 5 huge boxes I saw, the coris wrasses, powder blue tangs, and cleaner wrasses were the only dead fish.
I won't support buying any of those. Even if I found one that ate brine shrimp, there are probably a dozen PLUS or so that had to die to get that one there.