Questions on zebrafish

[Paul M Stokes]

Hi,
  I am an intern at UNLV researching zebrafish. I have just started my
project and I need eggs quick. We are having trouble getting them to 
breed. What is the best female to male ratio? Should the marbles be in 
plastic dishes or should they cover the entire bottom of the tank?  Should
the excess food be cleaned out every day? And should the brime  shrimp be
live or frozen? What is the critical factor in breeding these  fish (maybe
there are some secrets)?  I've read a lot of articles on  the net but
everything seems to be different. Please let me know the  most effective
way. Thank you.
Paul Stokes