I have had luck with my endli being 5" and putting her in with a congicus that was 12" & another endli that was 9". Right now I got 2 weeksii at 7" with that are cohabitating with 2 congicus 13", 2 endli 13" & 10", 2 koliba 16" & 12". The weeksii have not gotten eaten so far. I just make sure that everybody is well fed. Only way to find out what will happen to try it. GL!