Tilapia aurea (Steindachner) were fed androgen (17a -ethynyl- testosterone) or estrogen (estrone) at 30 ug/gm or 100 ug/gm of diet, respectively, for 22 days in steel troughs. Daily feeding was Purina Trout Chow, 12% of body weight divided into three equal portions. Untreated Purina Trout Chow at 10% of body weight was fed in rearing trials in both concrete tanks and earthen ponds once a day, six days a week. One hundred percent males were produced with the androgen in Trial I and 90.3% males in Trial II. Estrogen did not produce a significant effect on sex ratio. Fish treated with androgen had significantly (P < 0.05) greater weight at four months of age, after having been reared in earthen ponds. There was no significant difference (P < 0.05) in weight when the fish were sampled at 2 months of age. Estrogen at the dosage level of 100 ug/gm of diet had no effect on sex ratio in T. aurea.