Hey everyone. Have a sick tang and am not sure what it is. I'm converting over from freshwater discus and am very new to saltwater fish. This powder blue is doing a lot of hiding and isn't eating. Been doing it for 2days now. I noticed today this discoloring on its left side face and cheek. Of course my first thought is that there is a problem. Can anyone help ID this disease/sickness and recommend treatment? The only meds I have on hand is Furan 2. Worked miracles on discus.