How bad is the infection?
In my 120g tank, my blue tang showed white spots (salt like) 2nd week of introduction. I chose not to treat, kept up water change. After 3-4 weeks, all signs gone. IF it had ich, the ich probably is still in the system.
I plan to treat only if more than 1 fish infected and infection alters fish behavior (never noticed my blue tang changed behavior).
I heard other disease/stress can show up as ich like symptoms. Also ich treatment itself can stress fish as well.
I am newbie, 5 minths into salt water.