High zane ,ooohhhh I've never heard of a bristlie being as wide as it is long- could
turn out to be an issue. As for getting her to spawn try throwing in some blood worm ,
and think about moving 2 of the males leaving the best guy for the job( less competition)
then hit the tank with a cool water change , these things should all help providing the size of
your fish is not a medical issue. What about your males , have they ever spawned a batch
of youngins before?
Hope it sorts itself out for you.
Cheers J