Cupramine at .5 is too high for any fish, IMO. (Although its safe for most.) Cu at about .35-.40 works fine. Also, fish should be eating and CU brought to the therapeutic level very slowly. If your worried about about the wrasse and Cu, tank-transfer is ideal for curing or preventing ich; IMO. However, it won't do anything for most other, though less common, parasites. All of my wrasse have been treated with Cupramine; but I know some folks have had problems and I'd look at alternatives. Larger wrasse, like hogfish, tuskfish, etc., handle Cu very well.