Bonded male rabbits fighting

Question
I have two neutered male rabbits, both brothers about 6 months old (neutered about 3-4 months ago) who were bonded after being neutered and got along great for about a month, and are now fighting.
When we first got them they were together, and after about a week began fighting. We separated them and then promptly got them both neutered and kept them separated for about 2 months after neutering.
After about two months apart, we began to re-bond them in neutral territory and things went great. Both rabbits began to get along very quickly and within two weeks were completely bonded and living together full time.
Since then they got in one fight over turf and were separated immediately for a few hours (long enough for them to calm down) and then when put back together got along fine again.
About two weeks after that, they started to fight again randomly (had been out all morning together, grooming and sleeping together) and have not stopped since (and because of that have been separated).
With the first fight, neither of them were aggressive towards each other, other than than the actual fight itself, but recently whenever they see each other they raise their tails and make a skunky smelling scent and seem very aggressive. The few times they were allowed to be together after the fight they both went out of their ways to attack the other one (running from across the room to violently bite the other one) and things get out of hand very quickly.
They both also seem to go out of their ways to go and harass each other through the bars of their cages (when one is out he will go to the other ones cage and chew at the bars or just stare at him).

I'm wondering if there is any potential reason for this ongoing aggression towards each other (seasons, hormones, environment?) or if I can do anything to try and get them to like each other again? Or if my best bet is to just wait it out and keep them separated for a few months then try again and hope this does not happen?
Any help would be really appreciated with this because I am really at a loss as to why they won't get along any more! They were extremely happy together before this and nothing environmental changed that would have spurred this fighting.


Answer
Hi,

seasons can still affect the remaining hormonal production in fixed rabbits.  We see this often in the spring and fall with our guys, we notice their behaviors changing - lots more digging, more activity, more energy and playfulness.

With two males it is common for squabbles.  It's also important to recognize the difference between dominance issues versus actual fighting.  If one is coming across the room to put a serious bite, not just a little nip to 'stay in line' or 'move over', then that's a problem.

If that is what's going on I'd give them a break from each other for awhile, let them see each other and be around the others' smell and everything, don't let them fight between the cages - make sure they are far enough apart so they can't reach the other, and give them a couple month break.

It is not the end of the world if they can't be paired together all the time. We had one 'pair' that just exercised together for an hour or so a day, and then we separated them and they had some exercise time apart (with us), and they had their own houses to go back to when it was over.  Worked out great. They enjoyed seeing the other at a distance and didn't feel lonely or anything.  Had their own space, had some common time.  Long enough to enjoy but not enough time to get annoyed.