I breed my own mice and mine last up to a year in the freezer and they are still nice and fresh. My method is a bit long but it works for me so I am gonna stick to it. lol here is what I do.
-First I wrap each mouse in glad freezer press and seal,
- then i put the date on each one
- then i put all the one size/date in a glad freezer bag
- then i put the freezer bag in a glad ziplock freezer bag
- then I put that bag in a paper bag
- then i puts it in a airtight container
- then then i puts the container in a freezer bag,
- then i puts in in a cooler
- then i puts in in the freezer.
LOL its a long process but will worth it. And to make it easier i keeps about 5 or 6 in a seperate bag so I got easy access to my mouse on feeding nite. Hope this helps.