It is whitespot and can be cured a number of ways. You will need to treat the whole tank. It can be cured with salt, methylene blue, acraflavine, malachite green, quinine, mepacrine, and a number of other meds. The spots you see are resistant to treatment and produce a vegetative form of the parasite that can be treated and you need to treat for about a week after all white spots have gone.