Males are the stinky ones, not the females. Their urine has a stronger odour than the girls, so if you keep too many males, it's just a stink you'll have to get used to.
Another great tip to keep the odour down is to clean often.
I hear it all the time; people complaining about the smell with their feeders, but they only clean once every week or two. There is no fast easy way to eliminate stink except for some elbow grease and limiting the number of males.
Beta Chip helps too.