A few things to add. Chances are all these cats are fixed, but typically this time of year, fighting will escalate among males who might not be neutered. Also add new toys into the group- (nothing with catnip in it though!)
Take some Rescue Remedy and about three times a day, dab a little bit under the chins and along the backs of all cats.
Play classical music, I know with my ferals, when I play harp music if they are getting aggressive, they calm down quickly. They also seem to like Bach and Beethoven. But Celtic music puts a few of them into a fit! Go figure....
Take each cat individually into another room at certain times during the day and just interact with them one-on-one, groom them, stroke them, play with them, lay on the floor and just talk with them. Sometimes, when you have so many cats, you start taking them for granted (not saying you do) but life happens and you get busy. Then they start acting out with each other to garner your attention- because they know you will stop what you are doing temporarily and break the fight up.
Hope these tips help. I use them in my household of 15 ferals.