The quality of gilthead sea bream from distinct production systems and geographical locations in Southern Europe was evaluated to differentiate aquaculture products from extensive, integrated and semi-intensive systems from the ones produced intensively. This work analysed the external appearance of fish, yields after filleting as well as nutritional, sensory and histological characteristics of the muscle. The results showed that the yellow-golden line between eyes and the shiny red spot on the gill cover can be important and easy criteria to discriminate aquaculture products. Trimming losses are higher in fish from intensive systems. Lipid content of fish from extensive systems was significantly lower than values observed for fish reared intensively. Samples from the integrated and extensive systems showed the best n-3/n-6 ratio, contrarily to intensive systems, but it is difficult to establish clear quality markers to differentiate gilthead sea bream according to the rearing system. Regarding sensory characteristics, the sea bream flesh from intensive systems seems firmer and denser, having smaller white fibres and higher density of fibres in the dorsal muscle. The taste and odour of fatty fish was less strong in fish reared in non-intensive conditions, but extensive rearing in earthen pond is more propitious to the development of certain characteristics related to the environment.