Oncorhynchus mykiss is one of the dominant freshwater salmonids farmed in Europe and North America. In addition, it is one of the most widely studied model fish species in the wild and in captivity. Yet, the living conditions and the husbandry systems that maximise the welfare of this species are still to be defined, developed and improved. This lack is quite incomprehensible, given the background and the availability of research performed on this species. The low FishEthoScore is mainly due to the dependence of fish in the diet, need of space, high levels of aggression, needs of substrate, stress under farming conditions and high levels of deformations. In addition, anadromous fish experience changes in morphology, behaviour and environmental requirements through their life history. Thus, husbandry systems and practices need to take such differences into account in order to achieve and maintain higher welfare standards throughout the life cycle of the cultured fishes. The development of new rearing strategies to optimise the husbandry practices, handling with special care and the establishment of a slaughter protocol would be a step forward to solve some specific welfare concerns. Finally, providing feed which does not contain any fish components from wild catch has proven feasible for this species in lab studies, so a protocol for application in farming conditions has to be developed.