When I use to wade for trout on mountain streams, we always gilled & gutted trout as soon as landed. Then we'd put them in a wet fabric creel lined with wet stream moss. This kept the meat really cool and fresh all day while fishing. Always tasted great. We only CPR these days, but if I were to keep some crappie to eat, I would definitely put them on ice immediately after catching, unless you have a good livewell.

The most important thing to consider is to treat fish like you would a carton of milk. That mind set will tell you all you need to know.