It will be tough at 1".
Seen side by side, you will be able to tell there is a difference to their "look". But positively identifying them would be tough for me. When you get to 2" it becomes easier but still hard. By 3" you should be able to easily differentiate. I have posted a number of 3" RES pictures in my forage pond thread late last year. You can see the orange dot on their opercular fairly easy by that size.
my forage pond thread two RES nominally about 3" long (guess) CNBG of that size will have broad vertical bands on the body.
example of CNBG about the same size At one inch both CNBG and the RES will display vertical bands. As the fish grow the difference in apperance becomes greater.
