Temperature is considered to be the most pervasive environmental factor that limits the temporal and spatial distribution, and governs the migratory behaviour, of marine fish. Thermal behaviour in fish has been studied widely but the underlying components that affect temperature selection are still poorly understood. Further, very little attention has been drawn to the study of thermal behaviour in polar fish. This paper intends to: (1) provide a brief overview of nonthermal components that may be linked to temperature selection in fish, (2) outline the rationale behind a current project on biological correlates of selected temperature in two Arctic marine fish species, the capelin (Mallotus villosus) and the polar cod (Boreogadus saida), and (3) present some preliminary results obtained from laboratory experiments using an electronic shuttle-box system.