Don't tell them you are shipping a fish. You are allowed to ship live fish.
Specific Requirements by Animal:
"Fish must be held in a securely sealed primary receptacle.
Primary receptacle must be cushioned with sufficient absorbent material to take up all liquid in case of leakage.
Primary receptacle and absorbent cushioning material must be sealed within waterproof outer (shipping) packaging."
Nothing says you need to poke holes they are so dumb. Up the fish is in a plastic bag come on people. I just print my own labels and wright contains water in plastic and parishable on the box. Then drop it off no question asked.