I have posted links to two other of my videos of green sunfish spawning and nest building. The latest video lasts less than 10 seconds but it diplays a behavior that you may have never seen. Green sunish and other members of the sunfish family (of which bass are members) can become territorial. They will chase away and sometimes nip at a fish if it invades their territory. If the fish fails to take the hint, they will sometimes flare their gills. On a couple of occasions I have seen two green sunfish have a "staredown" where they go to nose-to-nose and flare their gills at each other. As for this teritorial/bullying behavior, it is not a male or female thing. A sunfish of any sex can bully another fish of any sex. Size does not matter; a smaller fish can dominate a bigger fish. Species also does not matter as I once had a bluegill bully a bass three times his size!