Personally I think quarantining a fish is a stupid idea, and I know people will differ with my choice, so if I were to quaratine my fish I would let them stay in there for a week or so.
like a month....maybe a lil less.....if they are wild caught fish deffinetly quarantine.....if not you can take the risk but you should deffinetly quarantine
without month-long minimum quarantine you will run the risk of exposing fish to internal parasites which may be present, yet not visible, like camamllanus which can take months to become visible, and hard to treat regardless. I'd quarantine minimum one month while including treatment for internal parasites on any wild caught fish
I would go anywhere from 2 weeks to a month. I see most people so far have said a month but I think anywhere between 2 weeks and a month is fine, it depends on what your comfortable with.