The concept of "quality", for fish as for other food products, involves many different aspects requiring various scientific competences to be studied. The biological basis of the technological, nutritional and organoleptic fish quality was reviewed. Technological quality is related to primary processing (gutting, filleting, trimming) and depends on fish morphology, distribution and composition of muscle and adipose tissues. Nutritional quality is directly related to flesh macro- and micro-nutriments composition. The organoleptic qualities gather the sensorial perception of the products including appearance, colour, flavour and texture. In order to manipulate adequately these qualities in fish farms, we focused on the different rearing practices, genetics, nutrition and rearing environment which can modify the fish characteristics and thereby the fish and flesh quality.