We all know how difficult it is to identify the sex of these fish, so please post a picture in here and we'll try to help you (or at least give an educated guess!).
Welcome to the site. I tend not to want to sex other people's zebras unless they supply a good shot from below and that shows the tube. Aside from that I use much bigger pictures so I can see the details of things like the odontile growth on the sides of the head and on the pectorals.
However, I would note that zebras are a warm water fish, the typical spawning protocol often has one take them up to 90F (32.2C). Ancistrus will not be happy at such warm temps and neither will most corys. Planetcatfish shows only one Ancistrus that lives at similar temps- triradiatus.
Next, zebras want a diet with a fair amount of meat, ancistrus need a diet tilted towards algae/veggies. To feed the zebras properly you will be feeding the bristlenose way too much meat as they will readily eat it.
I am assuming your goal here is not to spawn these fish in this setup?
Edited to correct spelling error.
What makes the common person uncommon is common sense.
