I was planning on adding bluegill but glad I held off! There are some grubs on fish in our area, I think the snail related grub comes is passed via the feces of the herons - which cant really use my lake because of the steep shoreline, and I dont see many snails - if any. I'll be checking for parasites this spring/summer just to see how things are coming along.
I dont have RES in this area - mainly just sunfish. Fun little things, I have some 9 inchers in the lake and they are pretty nice to watch. When Im snorkelling they follow me - I look behind and there can be hundreds of them.