I am planning on setting up a larger tank this spring which will incorporate as many of the species I can to reproduce the environment of a small stream. If anyone else is interested in the same kind of project, I would be pleased to correspond. Basically, what you will find is that they are strictly seasonal spawners, spawning in the early summer as the water is warming somewhere around 18 to 22 oC or so. Doing this we've got them to make nests but never spawn. Re sexing bluegills.
Males have deeper bodies and much more color than females.
The females generally have vertical bars on them and the males develop a deep orange breast area when they are ready to spawn. Males will make nests in the substrate. One trick that we found was to put a line of plants or other stuff in the tank partially blocking off about a foot of the end of a tank. A male would then take over this end area and start nesting. Write me back if you want more info.