Should I separate zebra danios sexes for breeding?

This is true because if they are separated the male's reproductive system is storing up and when they are back in contact with the opposite sex they will be more prone to mate. I would keep pairs in separate tanks that way nothing will eat the eggs while she lays them. Than once you see the male fertilize them remove the male and female so they can not eat the eggs or developing fry. Hope that helps and good luck with your possible fry!