one of the biggest problems with anthias is cyanide poisoning. I purchased 13 and had 7 die.. I got one tested at my friends lab... cyanide. Bought 6 more from a different supplier... 3 died... cyanide again, my buddy said his liver was "gross looking"
But back to the question... I have used prazi and copper to treat my anthias succeafully.
The are often caught with cyanide because they are VERY difficult to catch, they immediately dash into rocks. I had to go fallow on my tank, got 19 fish out, it took me 7 days!! to get the last three anthias out, they all hung around the last rock I had in there. I literally had to hold the rock out of the water and tickle them out of there holes with a chop stick.
good luck, I love my anthias school!!