You can pretty much tell if it's a wild or hatch when fighting the fish. The wilds just go ballistic. A 3 or 4 pound wild fights like a 6 or 7 pound hatch. When hooked they just start jumping and zipping up and down the run, can't even compare.
SERIOUSLY....so from what you are saying I don't even need to look for an adipose fin, bonk that coho cause it didn't fight like a wild!! Every fish is different; some go crazy right off the bat, some bulldog it till they get in close then go crazy, and some are just plain weak and give up right away.
I get a kick out of seeing/hearing a guy call it before actually seeing the fish. "Must be a wild, it's fighting real good!"...haha, c'mon seriously??
Seriously though, coho aren't that great most times! Most of the battle is right after the strike where they are rolling and flipping and maybe a couple short runs but done after that! I personally think excluding steelhead, Sockeye "properly" hooked fights better!