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Mice/Can you keep males together?


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Hi, I have a big 3 story cage and I keep 2 females and a male in it. Both my females had babies, a litter of 8 and a litter of 6. The babies are 3 weeks and 6 days old. I'm buying a big 20 gallon for all the female babies once there weaned then when my pregnant female has her babies and those babies are weaned the'll join my females in he 20 gallon. My question is well i would like to keep the males as well but i can't afford to buy them all there own cages so if I got another 20 gallon tank would it be ok to put the males together? I understand that males fight but if i give them a big enough space so they could have there own territories would that be ok? also when my pregnant females litter is weaned would those males be able to go into into the tank with the older males?

Hi Hadley,

A 20 gallon tank is not really enough for more than about 4-7 mice.  I don't know how many of your offspring are female, but I would think carefully about keeping a male with the females, as females can become pregnant the same night they give birth, leading to overlapping litters, undue stress on the mother's health, trampled pups, and due to your proposed caging situation, potentially unhealthy crowding.  Breeding can be a very expensive and tedious project!

Males from the same litter can be kept together, but that is not a guarantee that they will not fight.  Whether they have their own territories (which may encourage territorial fighting) or are crowded (which would cause additional stress) does not make very much difference to the outcome, although you may want to consider the extra space for number of mice alone, especially since males can be much smellier than females as they mature.  Siblings may do well their entire lives, or, if they start fighting at all, you may find yourself needing a new cage overnight to prevent a death.  Once males start fighting they must be separated, so you will need to be as prepared as possible.

Males that have been separated or were not raised together should never be introduced, so unfortunately, it would be unwise to merge litters born at different times.  It is important to remember that even between males who do not fight aggressively, when they are near other males they become very stressed, and this can lead to lowered immune systems, depression, and anxiety.

I hope I helped to answer your questions, and let me know if I can help with anything else,


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I can answer questions regarding mice as pets, mouse behavior, color and coat genetics, breeding techniques, and general health questions. I can help with caging and setup, nutrition, social issues, and what to do in most mouse emergencies (such as unplanned litters, injuries, fighting, etc.). I can also assist with questions pertaining to orphaned mouse pups, weaning litters, and questions of mating and birthing. I cannot answer questions about exotic or wild varieties of mice such as spiny or pygmy mice. *****FOR EMERGENCIES, anything requiring immediate medical intervention, PLEASE take your mouse to a professional veterinarian or wildlife rehabilitator who works with mice as soon as possible! IMPORTANT RESOURCES: Raising Orphaned Mice: Orphaned Mice Videos: Natasha's Your First Mouse: General Mouse Help: Mouse Info and Exotic Breeds:


I have enjoyed the companionship of mice nonstop since 2004, and spent a year caring for them in a lab where I learned a great deal about their breeding, social needs, and health. I spent a few years breeding them, specifically working with albinos, marked mice, angora mice, and satins. My education never stopped - I am learning something new every day from current and well-established research thanks to the wonderful folks at the Jackson Laboratory, as well as from my wonderful mousey friends online. I also love learning from my terrific questioners here on AllExperts - you folks keep my passion for these amazing animals alive and well!

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