I have some large-mouthed sunfish in one of my shallow duck ponds but want to be sure that they are warmouth and not green sunfish, thus my question about dark lines radiating behind the eyes as a distinguishing feature of warmouth.
Cody Note - RAH - green sunfish even 2" long will always have at least one or a few turquoise radiating lines from the eye back across the gill plate. Look closely size of streak varies. I think the large mouth sunfish in your duck pond are 98% likely to be green sunfish. Look at their gill covers and you should see emerald, blue green streaks backward behind the eyes especially on those 3"+ = GSF.
Examples of emerald streaks on gill plate of GSF
http://txstate.fishesoftexas.org/lepomis%20cyanellus.htmhttps://www.outdooralabama.com/bream/green-sunfish
