In this paper we present a previously unpublished compilation of data on inlet-water quality in Norwegian and Chilean smolt production. The data may serve as input to design suitable water treatment strategies both to avoid potential problems related to inlet-water quality, and to attain the desired buffering capacity and ion-composition in RAS systems. In addition, intensity parameters in current production are presented, that illustrates a need for further technological development to obtain an optimal production environment in smolt production.