The truly silly thing is that there is no need to grow monosex fish. If you grow them in simple mesh covered cages made of PVC pipe the keeps the fish from finding a flat bottom, they can't spawn. This allows the females to put their energy into growth rather than raising fry. Females grown in cage culture will get as large as the males and you'll have no recruits.

Cross species hybridization is a lot of trouble as you need to keep two separate strains of pure fish, but the rate of growth makes up for it if you are doing this on a large scale.