Do you ever have those times when you intend to release a fish because it was too small or any other reason, and end up killing it in a slow and agonizing manner?
Happened just the other day when fishing for trout. Caught one that was too small for my liking, and attempted to release it to grow some more. Tried to get it to hold still, but it kept flailing around on the platform for several seconds. By the time it settled down, I reached into its throat with my pliers and pulled the barbed hook out, which must've torn something and caused it massive bleeding. Tossed it back into the lake, and soon found it floating belly up with a cloud of blood around its head.
Figured it was finished so I attempted to retrieve it with my arm and keep the catch so that it doesn't die senselessly, but it slowly swam away into deeper water and held a belly up posture there for a few minutes.
Explained it to the guy at the tackle shop what happened, and he told me that it in all likelihood died from blood loss.