You need not practically have a "tank" to quarantine your fishes...
A Ikea Container with a sponge filter and a airpump will do a fine job...
As long as the container that the fish in is big enough for it..
Regular water changing is a must, once every few days, siphon out the leftover food and clean the filter...
I wouldnt say medication but as a preventive measure it always good to add some Furan in the QT and it is not toxic to corals and invertebrate, so even if it leak into your main tank, there wun be much of a problem...