I used to work in an aquarium shop and can attest to the trigger's tenacity. Once, and this is even less-related, I saw a child in Hawaii trying to pull a trigger out from between a couple of rocks. They can really wedge themselves tight. Anyway, the kid pulled and pulled for a while and eventually gave up. After the kid left, the fisk un-stuck itself and swam away, looking as if nothing happened. I think different species have different tolerances for abuse. Bass seem pretty tough, catfish even moreso. The striped bass I used to catch seemed more fragile.