Ok this is thew set up :
Regal tang has a few white spots about 20 in total is feeding well and does not seem stressed in any way.
All other fish are fine so what do I do?
150 gallon tank with a large number of soft corals.
I would watch closely for a couple of days, if more show up, or fish seems to exhibit more problems, then move it to a separate Quarantine tank and treat
