Lately my Black Moor Goldfish (Sylvester) has been gulping a lot of bubbles. Now he stays at the top of the tank and doesn't move a lot. (By the way, I don't think he has Swim Bladder because he isn't swimming on his side). I also think he has fin rot, because his fins look very frayed and the ends are white (read above: He's a Black Moor). What do I do?