well, you sex them from top view, its like, their...hip bones are fat. its kinda hard to explain, if you show me pictures of your juliis (top view) then i might be able to sex them, but if you ask the cory experts (ie. clothahump) or go onto
www.corydorasworld.com, im sure they'll be able to sex them. but first they'd hasta reach that large size to be sexed. id rather breed your albinos (you can get bronze or albino to pair with it) since they are the easiest cories to breed