I am in no way condoning what was attempted here, but I have to admit that I regularly used USPS when I ran a hobby tropical fish hatchery in my home. I do remember one exchange with a local postal clerk when I was shipping a 10" goby from Massachusetts to Illinois via Express Mail. The fish was large, so there was a fair bit of water in the bag. And because you only fill the bags half way for gas exchange, this on-the-ball clerk felt the weight of the package shift and heard sloshing.
Clerk: "What's in the box?"
Me: "A fish"
Clerk: "Frozen fish?"
Me: "Gosh, I hope not"
Clerk: "Did