In my water most of the time I can not tell. It usually is pretty turbid from algae growth.
That said, I do occasionally see a fish that I can identify as a RES from the bright red opercular tab border. But that is rare to see one.
I do notice GSF or hybrids thereof compared to BG because of the tipping on the fins. They stand out in contrast enough when they are up in shallow water that they are pretty easy to differentiate. But get out to a couple feed depth and I usually can only see shadows of fish or nothing at all.
