Optimal sex ratio in tilapia breeding ponds depends upon stocking density. However, under certain circumstances, altering the male: female sex ratio from a more or less natural 1:1 to 1:2 or even higher has been shown to increase fry production in oreochromiines. The research reported here was a first step toward establishing the broodfish sex ratio that Malawian smallholders ought to use to produce the maximum number of 0. shiranus fry under local conditions.