It is not easy at all for a layman to ship a fish on a budget, even if not a large one, even if without the spines and teeth. It takes practice, much, much practice to get into the 90%-95% success rate. Meanwhile, one must eat the losses.
Take yourself as an example. Perhaps it is a typo, but it is not air the shipping bags are filled with. See, even the basics elude people, what to say about finer points of know-how to ship?
In an analogy - what's so hard about driving? You place in gear, steer the wheel, push at two pedals when needed, and watch the traffic in front of you. What's the big deal? Piece of cake! A half-wit can do it! But if you just get in and go, you are much more than likely bound to buy the nearest farm or kill someone and yourself.