My Emperor angel developed Cryptocaryon after last Sunday's water change. On Tuesday he had some white spots, I could easily notice it thanks to the tank lighting, so all I did was feed him even more, and turn off the lights to reduce his stress. Wednesday dawned clean, and until now the white spots have not returned, I'm going to leave the lights off tomorrow too, the fish is feeding impressively, finishing a bucket and a half of PEmysis and shellfish porridge, in addition to the flaked food . His tummy is maybe 1/2" thick, he is fat and healthy.