Die deutsche Version dieser Seite ist etwas auführlicher und meistens auch aktueller. 
It is only a short time that I have African Pygmy Mice, but since I found nearly nothing about them on the Internet I would like to share with others what I have found out.
I bought a group of three males and three females. After some hours of transport in the car temporarily I put them into a 20 x 30 cm² box. On the next evening I noticed that two older, bigger males chased around and attacked the third, smaller (younger) male. It had many biting marks and a large wound on one side. One ear was bitten off completely.
Instantly I put them into a greater tank (30 x 60 cm²). After that the interactions between all the animals in the group looked more quiet than before, and the small one no longer was bitten. But still it was chased away whenever it came into the way of one of the two older males, especially they always drew it away from the food. For moments the poor thing sat miserably, shivering in a corner, then it was again chased away. It looked as if it might no longer be bitten to death but be killed by hunger or stress. So I took it out and kept it singly.
It could be seen that switching from the smaller to the larger box reduced the level of aggression (biting stopped) because the chased animal could get some distance to its attacker. More hiding places did not help, it was necessary to have enough room to get out of the way. But nevertheless, I have no doubt it would have been killed in the end. The remaining group up to now is stable and the single one has recovered remarkably fast.
So - if you have brought your new group home you should have an eye upon them for some days. Later on I found old bite marks on one of the females, which means that there must have also been fights in the breeding group from which it came. The ears seem to be the first part of the body which is attacked. Accordingly the biggest of my males has its ears nearly unharmed whilst the others have smaller parts missing. But, as I said, that must have happened earlier in the group where they were taken from.
Mainly I feed millet, additionally dried gammarus (turtle food, looks like tiny prawns), and small amounts of linseed. Also they always get fresh small cuttings of cucumber. Other bird food with small seed mixtures can also be fed. They don't like large seeds like wheat or rolled seeds and leave them in the food dish. I was warned that a lack of animal protein can lead to cannibalism. A lack of vitamins can lead to serious problems (loss of fur, staggering, maybe even loss of the tail), therefore I always give them cucumber. Also apple is eaten, but carrots and different sorts of green leaves are left over. A mineral block I don't use since the gammarus are said to be also a good supply of minerals.
Fresh water must also be available and is consumed in (relatively, of course) large quantities. Temporarily I use a one way 10 ml plastic syringe as water bottle: the nozzle for the canula cut off, filled with water with some air above to allow pressure balance.
In Europe I suggest a layer of the usual pine/spruce shavings, in the US where pine seems to be more aggressive than in Europe (or here they don't use pine at all but only spruce) you should try to get aspen shavings ore use only card board and toilet paper. Since they urinate also into their nest the nest tube should also be placed on a layer of shavings. A little hay and teared toilet paper make good nesting material. African pygmy mice don't shred everything to pieces like gerbils, so corrugated card board can be used to make them lots of small tubes as house, hiding places, tunnels, and bridges.
The urin of African pygmy mice seems to have special properties. On surfaces it often forms large, well formed crystals. On nesting material it seems to work as a sort of glue and also stiffens it, so that tunnels last which are made of impregnated leaves, toilet paper, hay and shavings. Also it seems to inhibit mold, even constantly wet places show nearly no mold.
I was surprised how tame the animals were in the beginning: Some of them hopped on my hand and climbed up the arm. But it is not easy to control this, they are so small and afraid of fast movements. Also they are said to easily get fatal inner injuries by handling. They can jump quite high, a lid on the tank (wire mesh) is absolutely necessary.
When I made the photos they were very irritated by the flash or the sound of the shutter. Since then they no longer come on my hand. But some of them still don't mind my hand being besides them if only it doesn't move fast.
Someone told me he got bitten when he lifted a female by the tail when cleaning the tank. Maybe catching them in a little tube is safer for both, mouse and man.
They are active only in the night but can be watched in subdued light.
Like Mongolian gerbils African pygmy mice sniff shortly for identification at each other when they meet.
The ears are very mobile and often move independently.
In my little group there is still peace, but generally these animals seem to be more aggressive towards each other than gerbils. They avoid touching each other (out of the nest) and prefer to have an eating place for themselves. Therefore it is a good idea to have several places with food in the tank, especially in larger groups.
Seeds are peeled where they are found, the seed kernels are collected in cheek pouches and eaten later, often in another place.
They prefer to drink by licking off small drops, but they can also drink from a small bottle or a shallow dish. The latter will become dirty with urine and shavings though.
They clean their fur very frequently and with great care. This regularly includes scratching. After scratching the claws often are licked, maybe to remove scratched off parasites (even if there are none, I hope!).
For the African Pygmy Mouse I found the following names: Besides Mus minutoides also Mus musculoides, in German Afrikanische Zwergmaus, and in Dutch Afrikaanse dwergmuis.
(which up to now I can only report, not out of personal experience)
I think the attacked female must have died of inner injuries or of stress, the loss of the tail cannot have been the reason. And together with my experience it becomes clear that it is a critical thing to make a new group out of a part of an existing group. The new social structure must be determined and apparently not always all new members fit into it. With future feedback from other readers I hope some time to know better what is a good constellation to start with. Maybe a pair of two is safer.
