From the same series of SRAC fact sheets. Recall that these are about aquaculture not recreational ponds and forage. The reasons are to prevent overpopulation and stunting , because males grow about twice as females and no wasted energy/investment from mating.


Species such as Tilapia zilli, T. hornorum, or T. mossambica are not suitable for mixed-sex culture because they reproduce at an age of 2
to 3 months and at an unmarketable size of 30 grams or less.Two to three crops of fish can be produced annually in the tropics
compared to only one crop in temperate regions.
Fish farming strategies that prevent overcrowding and stunting include:1) cage farming where eggs fall through the mesh to the pond bottom before the female can collect them for brooding; 2) polyculture with a predator fish, such as fingerling largemouth bass, at 400 per acre; and 3) culture of only males(monosex). All-male culture is desirable in ponds not only to prevent overpopulation and stunting but also because males grow about twice as females.

Male monosex culture.
Males are used for monosex culture because male tilapia grow faster than females. Females use considerable energy in egg production and do not eat when they are incubating eggs. Male monosex culture permits the use of longer culture periods,higher stocking rates and fingerlings of any age. High stocking densities reduce individual growth rates, but yields per unit area are greater. If the growing season can be extended,
it should be possible to produce fish weighing one pound (454 grams) or more.

The rates and numbers and weight gains in these papers should be viewed in the context as written wrt aquaculture operations not recreational ponds unless so specified in the article.