I'm pretty sure by keeping your fish indoors,you will break the life cycle. The spots may not go away but will remain encysted but should not cause a health concern.
Doesn't look like Black Spot to me, which was my first thought when I saw the title. Watchful waiting is what is needed here. No sense treating for treating sake.
I personally like to add Zeolite in this situation. It will remove nitrates slowly over several hours to days, opposed to massive water changes.....Just never add Zeolite to a salted tank.