Water temperature and photoperiod only or with HCG injection are the most important factors driving sexual maturation in fish. This study investigates the possibility of induced spawning of Gilthead Sea bream in captivity by exposing to program of water temperature and artificial photoperiod with or without HCG injection.  A total number of 60 Gilthead Sea Bream were collected and kept in indoor fiber circular holding tanks filled with salt water, under controlled photoperiods and temperature. They were divided into two groups. The first group was exposed to water temperature 21.5 to 18 °C and artificial photoperiod programs (control). The second group was exposed to water temperature 21.5 to 18 °C and artificial photoperiod programs and injected with single dose of HCG. The experiment conducted for 4 months. After the end of the third and fourth months, and after 24 and 48 hours after HCG injection, K factor, gonadal weight, gonadosomatic index (GSI %), fecundity and egg diameter were measured and blood samples were collected. The Results of gonadal weight, fecundity, egg diameter, LH and progesterone levels were increased in injected group when compared to control while the results of GSI, and FSH showed significant decreased (P<0.05) when compared to control. It could be concluded that HCG injection in single dose (1000 IU/Kg BW) aiding with water temperature and artificial photoperiod programs induced increasing the maturation of gilthead sea bream in captivity.