When a fish is in quarantine, it's best to observe. Nearly all the medications on the market cause stress, and some cause undesirable side effects. A few things you can treat with our stress coat marine, and anything aloe vera based that aids in healing damaged fins and tissue. If a problem arises, it is very important to properly diagnose and treat, based on what is taking place. Many people create a chemical soup of un-needed treatments, that ultimately do more harm than good.
Some folks run their quarantine set-up in hypo-salinity. This is an option, as the lower salinity aids a fish in osmo-regulation, providing a relaxing atmosphere. This also kills any parasites, but doesn't harm bio-filter. Hyposalinity is about 1.010 specific gravity, and you need to balance your ph to around 8.2 with buffer if you choose this route. Just remember, a hypo quarantine is only safe for fish. Any coral or invert, will perish in hypo conditions.
While quarantining I recommend feeding a diet of food fortified with both Selcon and Brightwell Aquatics Garlic Power. I used those on all my fish feedings, but they can be crucial helping a fish recover from the stress of capture and shipping.