Overfishing of natural populations along with increased market demand for fish, imposes the need to increase aquaculture production and improve farming technology and methods. Demand for fish quality is also becoming more highlighted on daily basis. Therefore, the aim of this paper was to review the existing scientific literature and to describe traits of quality and methods of its assessment plus postmortem changes in fish meat and factors that negatively affect them. In addition, changes in behavior are described alongside other factors indicating welfare/stress, which can indicate irregularities in fish farming that could, if not corrected, negatively affect the quality of the final product. The spoilage rate of fish meat may be reduced by good husbandry and handling practices combined with hygiene procedures which are manifested by the speed with which postmortem changes occur. These changes are divided into four phases. It is necessary to prolong the first phase, the phase increased mucus secretion and rigor mortis, as much as possible, because then the fish is at its best freshness. Rigor mortis usually occurs within several hours after death, depending on a number of factors such as: species, size of the fish, geographical area where fish was cultured, the amount of stress to which fish was exposed during farming and harvest, as well as postharvest handling. Stress caused by any type of stressor (biological, chemical, physical and manipulative) influence energy consumption, and presents the main factor that needs to be reduced during farming and harvesting. This is achieved through technological measures, especially trough maintenance of the optimal quality of rearing environment, adjusted to stocking density, proper feeding regimes, and careful handling. Therefore, in order to preserve the quality of fish meat, it is important to rear the fish in adapted conditions specific to the species and to handle it properly in compliance with all hygienic measures. Harmful factors (stressors) will be manifested in reduced welfare which can be observed not only in physiological responses but also in behavior of the fish. That is why it is utterly important to notice any change of behavior on time. Good manufacturing practice, in addition to ensuring a quality environment and rearing conditions, must include the proper handling of fish during and after harvesting. This includes a convenient method of stunning, hygienic and proper handling of fish and continuous maintenance of the cold chain from to moment of catch to the final consumer. Therefore, it is important to reconcile the interest of the producer, which represents an increased growth rate at high densities, and the requirement of the cultivated species in order to obtain the optimal ratio of quality and quantity of the desired final product.