Monosex fish culture is advantageous for fish production and industrial benefits. Therefore, the aim of this study will investigate the control of sex and feminization in cobia(Rachycentroncanadum) for improving the industrial efficiency. At present, eight fish of cultured masculinized cobia, an average weight of 3136.75 ± 777.89 grams has spermiation , but the amount of sperm production is insufficient for artificial insemination. Although the use of aromatase inhibitors to promote sperm production, but the effect is not significant and semen amount was not enough for cryopreservation and artificial breeding . We expected in the next 2 to 3 months to complete the above steps, and then cultured progeny until 100days post-hatching to identify the sex ratio of offspring by gonadal histology, then to confirm the neomale cobia. These neomale fish will spawn with normal female to produce all-female progeny. These results can be applied to cobia aquaculture.