Hello - My Oranda goldfish have white bumps and white patches at one point on it's fins. They have been there since the last 4 months. They look like pimples (attached). The fish doesn't scratches itself and acts the way it always had before having the bumps (i.e. swims perfectly, eats, doesn't act sluggish). I tried salt water bath, melafix and pimafix, general cure but nothing helped. The water parameters are good too. I am really confused what this pimples/bumps/patches could be. Should I be worried?