When buying fish, the safest way to receive "disease free" fish are when they are eggs. Eggs can be disinfected quite easily and as stated earlier, they ship fairly easily. Assuming no genetic disease/virus is passed on vertically (parent to fry) the fish will be technically disease free. In the commercial aquaculture industry, this is how majority of the fish are shipped (or when extremely small). I have been wanting to try it with discus eggs for quite some time....just havent had the time to do it, lol.
-Ryan
-Ryan