What do you mean medicated food? Post the type of food, or are you medicating food yourself?
And my recommendation if the fish swims well, and eats well to dose copper power or copper safe at 2.25ppm min right away. Why wait? If it’s a carrier of anything why not be on top of it. I know some where will say why even QT. Simple answer. Do you know for sure if it’s a carrier of let’s say velvet? And is it far fetched for marine fish to come installed with velvet? Answer is not at all. UNLESS….. you have a trusted source for your fish. And even then, still never know, but it’s less likely.
Either way, fish these modern days seem so loaded with about everything. I just don’t trust anyone anymore unless you’re buying QT’ed fish, and I don’t have the time and energy any longer to chase fish in a tank to QT them, or run the management method for at least ich. I get you can manage ich, BUT I stand by what I wrote above…. What happens if it’s velvet that makes it on the fish? How you manage this model of disgusting disease? Answer…. You can’t. So back to my statement, I don’t have time and energy to deal with a DT that ended up getting hit by disease.
My new tank thread, you can see my fish bunch all healthy and not a single disease spot on them! And never will there be anything that goes into that tank without being ran fallow or QT’ed.
So if the fish is doing good, my recommendation is to get copper in that QT tank. Why wait? I can’t find a single good reason.