Just read through this entire post with great interest...I think I have a pond with RES X GSF hybrids...I'll take pics and post but I've caught several of them that have the gape and coloring of a GSF but clearly have a red opercular tab - just like RES.

This pond has had both RES and GSF for many years.

Pics to follow.

Dale

[Linked Image from i90.photobucket.com]

"When tempted to fight fire with fire, remember that the Fire Department usually uses water." - anonymous