Possibly a squirrel when I was younger. I shot an arrow at it and saw I deeply grazed its belly (I was both proud and disgusted that my aim had improved that much). I would not be surprised if it had to battle an infection, which resulted in either death by being eaten or death by the infection.
But as far as animals I've watched die, an 8-inch brim I caught once. The hook was lodged too deeply into its skull and the act of trying to remove it only tortured the thing, so it had to be killed. What a waste as I do not think the water was clean enough for eating those fish.
I don't like killing animals--it makes me shiver all over and want to cry in shame. If I were eating said animal, I might not feel so terrible about it.
"I took the one less traveled by,
And that has made all the difference."