if you had ich on the fish, you would notice it, it presents itself as little salt flakes on the skin of the fish. the pic is a little fuzzy but i can see the a the white protrusion...it may be pop eye or can also be an infection from an injury to the eye. sometimes fish will rub close to a rock and scratch the eye which then gets infected...make sure the fish is eating. keep a close watch on him and tank mates for similar symptom. how long had the bubble been there?