Entrainment of the circadian activity rhythm in the juvenile trout,Salmo truttaL., by red light

Abstract

Some fish have a good vision in red light, although this spectral bandwidth is rapidly absorbed by water. The question thus arises as to whether those wavelengths could entrain the circadian activity rhythm in juvenile brown trouts (Salmo trutta L.).Photocell technique records in L.D. 12-12 show that rhythm is entrained when red light is used.