If the gills are still red to pink, I clean. If they're white, I toss. However, I keep a cooler with ice in it, and if any in the livewell start getting that faraway look as mentioned or die, I put in the ice chest right then.

I can remember when I was a kid bringing fish back on a stringer in the trunk of the car on newspaper, and imagine the days when people walked a mile or more back from the fishing hole to get their fish home. We did clean them immediately on our return back then.