Has anyone had success with shipment using breather bags? I am planning on sending some goldfish on Monday using USPS flat rate service. My understanding is fish will last up to a week in these bags without incident. Also, according to the USPS website, they will only ship fish packages that have been packaged with a waterproof sealant. I'm guessing an extra thick garbage bag should do the trick - but wouldn't this block oxygen from permeating into the breather bag, which defeats the purpose of said bags? Has anyone shipped in the past under current conditions with success - what did you do to satisfy USPS' shipping of live fish criteria. Thanks in advance.