3 mice of same litter but one is overweight

Question
Hi there,
A few months ago I bought three female mice who were from
the same litter (what I was told anyway). They were about
six weeks old. One of them however (orange and white) is
quite overweight. The others are very tiny. I have been
concerned for a while but I dont know what to do. I dont
want to feed them less because the others are quite tiny. I
feed them a mix you get from a pet store and occasionally
they get bread, pasta or vegetables. Just wondering if I
should be concerned about my mouse being overweight and what
I should do?
Thankyou

Answer
I have come across mice that over eat which is not good to the rest of the litter as they will starve and their bodies will not develop properly
I have also come across mice that are pregnant when bought and drop a litter within 3 weeks of buying the mice
It might be an idea to put a temporary mesh divider in the cage and monitor the big mouse's diet and size and consult your vet about possible internal problems or to confirm a pregnancy as mice can get pregnant at a very early age.

Bread is high in sugars and carbohydrates and is not recommended for an overweight mouse.
Their main diet should be a good quality hamster mix a little vegetables once or twice a week and vitamins in their water.Give them wood chew to gnaw or even a small hide dog twist chew. Also introduce a couple of solid plastic exercise wheels and some toys to climb on.
Pasta is also no good to them.