I've had this Angel for 4 years and never a problem. Some months ago I moved tanks and the new tank had an ich outbreak, So the water was treated with copper(This may be unrelated). All fish in the tank recovered and are now eating without any problems. But since 10 days ago my queen angel hasn't eaten anything. Tried seaweed, store brand, home made food but nothing will get them to eat. Maybe 2 weeks ago there was a strange problem with their mouth looking like it was stuck open, it only lasted a few days and they look normal again. I'm worried now they are going to starve themselves to death. The salinity is 1.019 and water changes are frequent. There are no other angels of course, just a Sailfin tang clowns and a wrasse. What can I try to make them eat again?