I have read that it is a good idea when you bring home a new fish to put it in a quarantine tank for a while before putting it into the main tank. Is this a good idea? If so how big should this tank be and should it be it's own system and not flowing water from the main tank? How big does it have to be? I have an extra 20 gal long tank can I use that. How long should you leave the fish in there (days, weeks etc)? I am considering doing this because I have recently bought a couple fish that have come up missing ( most likely died) and I don't think it would be a good thing to tear the tank apart to find them. 1 was a blue eyed tang and the other was a yellow eyed tang. They seemed to be fine (swimming, eating etc) and everyone else is fine and water params are good. I have tried to look between the rocks and most of the visible places but do not see them (swimming or laying). I feed the tangs both Rods food and give them algae strips. Thanks in advance for any info.