They'll be fine. When I had to ship a ton of boxes off to the breeders after our show last month, a couple had gone priority. I shipped on Monday and on Thursday I got an email from a guy still expecting his show fish. They finally showed up on the following Monday, all alive and well. One week in the box AFTER having to travel to me via priority and AFTER two days of sitting on my table plus two to three days of being in show. So they'd gone nearly two weeks without food and they did wonderfully on the way home.