I had to separate them late last night! D:
I found my tiny boy, who were on weight watch to make sure he gains some, had gone down in weight! I checked him close and found a good number of small scabs from bites and/or scratches, and his cosy hole was full of pee and poops so he never left to defecate and not enough to eat D:
They were all very superficial and seem to heal nicely, so he should be OK, I'm more concerned about the weight loss. He is such a tiny boy, was 360 grams, down to 344 grams. He is happy and healthy and one of the most active of the bunch! Vet told me to just monitor his weight and not to bring him in unneccasary, and I know what caused it so wont put him through that stress unless I have to. He seems very happy and eats well in his new cage, but did call for his friend.
I separated them all emedeately. Tiny one to my bedroom in the girls' old cage for peace and close monitoring, and then I switched the two other boys woth the girls as the girl cage could be closed of in two separate areas. Had to clean out their cages first since it was cleaning time today, felt it was wrong to wait. Got to bed at 2 am :p *worth it!*
Their behavior seems to be directly influenced by noticing the girls. The biter is the one who was super focused on the girls. He never chased them before that. He sat all day in the best spot to see one of the girls while making sounds I hadn't heard before, and only left to chase the others.
I never found fur slips in the cage untill cleaning, and even then there wasn't much. I'm keeping them separated for now and will consider slowely trying to put them back with the girls moving to the other room as soon as it becomes available again this weekend (friend moving out). They got along wonderfully for a long while after all. I do have cages enough to keep them separate for all their time if needed, but together is preferable, if only the two original ones. The "biter" is twice their age and introduced this fall, but with no agitation at all. They huddled up together the first night we let him in to their cage (after slow introduction with cages next to eachother and play sesions) I'll try slowly, but keep my tiny one separate untill he gets better. I tried to separate him from his friend before due to his weight and it made him loose more weight cause he missed his friend, but I feel he really should be alone this time. All three called out for their friends yesterday, it's such a sad sound. The girls did it too when I kept them separate for pregnancy watch (it has been well over 111 days now so they can be kept together again)