I have several fish in quarantine now, tomorrow is a week old with chelated copper at a concentration of 2.5ppm I started with copper because I had a fish swimming in front of the wave maker and it turned dull in color. Now I have seen improvements in that fish, but other fish that were not scratching are now scratching... how can I tell you, the copper concentration has been at 2.5 ppm for a week now... do you think they could be flukes too? Or why will other fish scratch that previously didn't?