[0] Protozoa (Skin Parasites) [1] Costia, Chilodonella, Trichodina, Epistylus [2] Increased gill movements, fins clamped to sides, lying on bottom, increased slime coat (white or grayish cast on skin) [4] Avoid adding the water from the bag of new fish into your aquarium, and discard the water in the fish bag. Quarantine new fish before adding them to your aquarium in a separate isolation tank. [3] 
Treat water with Formalin, Malachite Green, Acriflavine or copper sulfate.