Hi there. Sorry your boys started fighting. It is the norm rather than the exception. If you can get them neutered before any fightinng then you have a good chance of them remaining friends. But this is too late for you so now you have had them neutered keep them separate for a month or so for hormones to subside and try them together again on neutral territory. You will have to keeo a very close eye on them because once boys have fought they usually do so again. It is very sad but it's what they do, I have had many brothers fine up to about 12 weeks and then bingo. I have a pair of brothers that managed to get to 5 months without falling out, so had them neutered and they are fine. You can have them neutered earlier but I chose not to.