fancy mice, 2 males

Question
QUESTION: hey,
ive had 2 males in a cage for about 6months now i brought them from a pet shop and was told they were from the same litter and that they had lived in that cage together since they were born. but recently they have started fighting alot, i seperated them for 1 night as i worried for 1 of the males as the other was picking on him - as soon as they realised they had been seperated they were talking to each other and i felt bad. the day after i let them out to play togther while i sat with them as i didnt wantr them to have no contact at all and they got on fine. i have a small cage that i put the in when im cleaning their main cage out and i decided to put them in there togther and watch them, they were fine - washing each other and slept curled up with each other all day. i thought they were ok with each other again so washed their main cage out and put them back in. they started fighting instantly. as there is too many places for them to fight in the cage that i cant get to i put them both back in the smaller cage and once again they were washing each other and curled back up with each other. what is going on and is there anything i can do?

ANSWER: Dear Leigh,
thank you for your question.
Male  mice will fight when they are kept together, that is normal. There are very few exceptions and usually the fights get serious very soon and can result in badly hurt mice. You can keep them together in a small cage that doesn't have many toys and no hiding places (those are always fought over), but that's not really a solution and they may fight in such a cage, too.

If you can find a vet who will neuter them or at least one of them, they can live together. Keep them in the small cage until they have been neutered for at least six weeks, you may need to take out almost all the furniture to prevent fights. After their hormones have calmed down, they will live together peacefully, a neutered male doesn't really behave like a male any more.
www.rmca.org/Vets has a list of good rodent vets.

Otherwise, you will need to separate them. They can be housed with natal rats or white-footed mice so that they are not lonely (both species need big cages!). It's not perfect, but it's better than spending their whole life alone.
http://www.centralpets.com/animals/mammals/rodents/rod2492.html

You said that they talked to each other, Do they really male sounds you can hear, like a squeaking or a chattering noise? Then you need to see a vet as soon as possible, these are sign of a respiratory infection that need to be treated before it gets chronic. Healthy mice don't make sounds that humans can hear.
I hope I was of some help to you
Jennifer

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QUESTION: this is the second day theyve been in the smaller cage now and they are fine. they are playing together and curling up and grooming each other like nothing has happened. i dont want to get either of the mice neutered as i dont think that is fair. as for the noises they making it was a squeak similar to when they fight but a panicy sounding one as this was when they had been seperated, it has only happened once.

Answer
Neutering is fairer in my opinion than keeping them in a small cage or alone for the rest of their life. They don't miss anything and neutered males are in almost all cases very friendly to other mice, getting along with everyone.  Once they have really fought, you won't be able to introduce them again, not even when they have been neutered usually. Keep an eye on them by all means, males often start fighting with no warning and the really serious fights are silent, you won't hear them squeaking then.