This is possible. However, you wouldnt be able to use popular medication that is more effective for certian treatment such as copper. You would have to use reefsafe medication which at that point, you could treat in your main tank. I want to put coral and rocks and sand in my qt so bad, but it would just make it incredibly more hard to treat sick fish.
Quarantining is a great measure to assure no diseases are introduced into your display tank. It also allows you to observe fish more easily and requires less use of medication opposed to medicating a large tank, access to the fish and less water needed for water changes. It does NOT limit medications but rather use of less medications. I recommend no smaller than a 20 gal long tank and 40 breeder as ideal.
When I said it limited medications, I meant if the OP ran a fish and coral QT. Out of curiosity, am I mistaken?
Just to put this out there - if the corals have ich tomonts on them, then having a fish in the tank will give the ich a host to feed on and enable it to reproduce, and you won't be able to treat the ich infection without killing the coral.
Not necessarily - it largely depends on the stress levels of the infected fish. Many infected fish don't show symptoms until they get stressed, then have an outbreak; this is part of why fish can be seemingly healthy for months or even years, then suddenly have an outbreak.
Many medications can be mixed but carefully or with precautions. One will not QT fish and coral together and should not for obvious reasons. Quarantining corals are becoming more common for reduction of risk of disease and is often asked with our MEDIC team although of low level risk. I dont quarantine coral but do dip and yet to have a disease breakout over a few decades now.
