# Aggressive mice?



## PazOtis (Sep 29, 2017)

Two questions in one here.

First, Pascal often plays fine and will sleep alongside Otis, but when just roaming the cage together, he will often nip at Otis. Wondering if this will resolve itself or if they should be separated permanently.

Second, Otis has always been extremely passive, not even fighting back when Paz picks on him, but a few days ago (after moving his cage to a new location), he suddenly became more aggressive. He bit Pascal's ear (the big reason they're separated right now) and would try to bite when I went to give him food or clean his cage. After being allowed to run around a bit outside the cage, he returned to normal. Wondering if he was just stressed from the new arrangement or if something else is going on.


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## SarahC (Oct 3, 2008)

once fighting begins with male mice they have to be separated for good.They often don't cohabitate peacefully together and when they do they have to be managed carefully.Some old bedding has to be retained each clean.Putting grown males into a new clean environment with none of each other's odors brings on the fighting.To try and reintroduce would carry a high risk of fatality to one or both.


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