Hi, I can't rule out Cryptocaryon, marine ich. The one spot on the caudal fin kind of pushes me to that diagnosis (fish do get white spots here and there, but a spot on the fin is often ich). Still, it could just be scale damage. The trick is for you to watch the spots over a couple of days. If they come and go, change location, it is likely ich. If the same spots are in the same location for days, then it isn't ich. Here is a link to background information that can help us make a better determination:
Aquarium Fish Disease Problem Solving Determining the best course of action for a problem with your aquarium can be a difficult task. Even advanced aquarists will often need to seek the help of others for complicated or unique issues. Our intent here on Reef 2 Reef is to offer expert advice...