Gilthead seabream (Sparus aurata) represents an important species for cultivation in the Mediterranean. It is a protandric hermaphordite. Males reach sexual maturity between the first and second year, and females between second and third year of life. At the age of 2 or 3, it enters with full maturity which implies maturation of the gonads. The total consumption of food in aquaculture must provide sufficient amount of energy building blocks needed for the maintenance metabolism, growth metabolism and reproductive cell production metabolism. Production results are assessed through survival, growth, and food consumption. Feeding efficiency is assessed by food conversion factor, and food consumption and growth are closely related. In sexually mature individuals, the increment, in addition to somatic tissue, also includes the growth of the gonads. In the phase of preparation for spawning, the growth of gonads contributes to the total growth of biomass, and with spawning this growth is lost. Biomass loss due to spawning has an impact on the increase of effective/economic conversion of food and on the change of the record state of cultivated biomass. Biometric data were collected for three different age groups of sea bream at spawning time. The measured parameters are: length and weight of the fish, the weight of the entrails and in addition, data on biomass and food consumption was collected. The estimated total consumption of food from the time of planting to the end of the spawning period for the 2018 generation is 1814.8 g of food per fish; for the 2019 generation, it is 1430.2 g of food per fish, and for the 2020 generation, the total consumption of food is 475.4 g of food per fish. For 2018 generation fish, the estimated FCR loss due to spawning is 9.94%, for 2019 generation fish the loss is 5.15%i, and for 2020 fish the FCR loss is 0.89%. The estimated biomass loss in fish from the 2018 generation is 4.63%; for fish from the 2019 generation, the biomass loss is 2.73%, while the biomass loss for the 2020 generation is only 0.62%.