Hi all, I need some help and I am hoping you guys are the right people to ask. I have a tank of 150 litres, it currently has 2 angelfish and one albino cory. Our newest angelfish (we've had it 2 months) has developed an ulcer in the side of the head. (Pictures attached) I only noticed it a week ago and I don't really know how to treat it, I've read many forums about the treatment of ulcers and am thinking I will go with medicated food, Pimafix or melafix but thought I would ask advise of the experts before I go ahead. Up until last week we had an extremely hyper angelfish and now he just hangs around the top of the tank, he's not able to eat and shys away from attention whereas before he would swim up to the tank window. I'm new to keeping angelfish but our oldest one is showing no signs of being affected and has been very healthy! Help please!