The minimum number of males per female that would still ensure high maturation, fecundity and hatching rates in Penaeus monodon broodstock, is determined. Wild stock P. monodon were stocked in 4 m diameter circular tanks at different sex ratios (0:1, 1:1, 1:2 and 1:4 male to female) for a duration of 55 days. All females were ablated on one eyestalk. Males remained unablated. The 1 male: 2 females ratio is recommended on the basis of highest percentage of first, second and third spawners, total and average fecundity. In the all-female treatment (0:1 ratio), 19.65% of the females spawned, but the 3.3 million eggs produced were not fertilized, resulting in a 0% hatching rate
