My fish sometimes get white spots on their head when they go break the surface of the water looking for food. There's usually a few microbubbles up there that they get stuck to their heads. Freaks me out till I realize what they were
Whitespot (Ichthyophthirius)= A very common disease (especially in a new aquarium). There are several formulas around, dose the fish quickly before the parasite spreads. Salt could be used (1 teaspoon per galloon).