was supplied continuously to the rearing tanks. weaning was conducted in the nursery unit where each experimental group was kept separately in duplicate 900L (0.5 m depth) circular tanks following routine rearing procedures for gilthead seabream the 55-to 60-day old fry(150-200 mg in weight were transferred from the nursery unit to the genetics experimental unit, where each of the pure parental and hybrid groups was separately stocket in 50 L circular plastic tanks (100-150) young fish/tank) for further rearing. the fish were kept in these tanks for 3-5 months before testing trials were started.