How old are your chickens? Are they all in a run together or do they free range? Right now we have 13 roosters and 16 hens. A lot of those are juvenilles so we don't really have any problems yet. Even before this years hatching season we had 4 roosters and 10 hens. Everybody gets along even now with all the new comers. But I think certain factors have contributed to this. One is that all the birds free range on our 10 acres all day. Another is having more than one food and water station. We noticed that when we have had fights in the past they have started at the "watering hole." All the hens would gather together in large groups to eat and the roosters would try to give food to the wrong hens and fights would break out (at least I think that is what was happening

. Once we added another place to eat and drink, the fights ended and they all live together nicely now. We also get up early to let them out of the coup in the morning so they aren't locked in a confined area together for very long after they wake up. Pretty much at sunrise everyday even on weekends. Generally with males of any species, aggression is caused by sexual frustration which is either relieved by mating or having enough space to get the exercise they need during the day to relieve themselves of the energy they save for mating. I am sure some roosters just want to fight more than others. If you have a rooster that doesn't fit your program and is disrupting the overall harmony of your flock I would get rid of him. Just my 2 cents.