Kay,
Creek chubs are often caught while fishing for trout and smallmouth bass. They will readily strike small lures and some of them get pretty big (8 to 10 inches). I don't know if they will eat your bluegills or not, but they surely can. I would assume that if the chubs survive in your pond that other species will as well. Judging from the ones that I have caught they are pretty delicate fish. I know that they will die if kept out of water very long while unhooking them. Check out this web site for some info on the minnow family.
www.dnr.cornell.edu/Sarep/fish/Cyprinidae/cyprinidae.html

Larry