My roosters were friends but now they hate eachother

[Chook-Beard the Pirate]

How old is the new bird?
Can you post a photo of the new bird?

If the new bird is female, your roosters are fighting over her. This probably will get intense with time. They can injure her by over mating her and could possibly injure or kill her.

the new chicken is about 2 months old

 

[NanaK]

the new chicken is about 2 months old

If you can post a couple good photos we may can tell if it is female or male. This can help you figure out what is going on.

 

[Ridgerunner]

we are attached to all of them so getting rid of one isn't an option. how do i get them to stop fighting?

When you add or subtract a chicken you can upset the social order they have established. Flock dynamics change. It is obvious that adding the new chick has upset the social order. I'm not that worried about why, could be different things, but it is obvious that adding it has. I assume when you say you are attached to them all that you are including that chick so you can't do the obvious and get rid of that chick. With your restrictions, what are your options.

Let them fight it out. They may reach an accommodation or one may wind up seriously injured or dead.

Permanently separate the two boys. House them so there is always a fence between them.
I do not see adding more chickens as a solution. They will fight over 25 hens as fast as they will fight over one. I'm not convinced the gender of the current chick matters anyway. It may just represent a "flock" to fight over. To me adding more chickens just means on top of everything else you have to also do an integration.