It works in the opposite way in some situations but often it requires the eggs and the milt to be fertilized artificially by human intervention. That is the way it is with GSF male x RES female. It does not seem to work in a pond setting but can be done in a petri dish. It also produces the most males with like 95 or 97 percent. The other way around, RES male x GSF female can work in the pond setting but is about 70 male - 30 female offspring.
Lots of articles I provided links in this thread:
RESxGSF hybrid
