Yes. Chances are the white spot (not ich, ich is a freshwater parasite) has released itself from the fish during the night (it's favourite time to do this) and is now in the substrate of the tank encysting into the theront stage. Next is for the cyst to realease around 200 to 300 infecting theronts which move towards light looking for a fish to host and when they find the fish the whole cycle starts again.
Do not put this fish in the display, it will still be infected the parasite is under the skin you won't see it until it starts to make its way back out again.
You need to get rid of the substrate, any inverts and anything else porous that will home the white spot in its theront stage and treat the tank with copper.