"Brownification" by dissolved organic matter (DOM) is common in Fennoscandian lakes. The conditions for vision are radically different in brown, dark water compared with clear, well- illuminated water. We analyzed possible visual adaptations and modelled relative visual performance of four common fish species (pikeperch, perch, pike and roach), each represented by samples from a brown lake (LT) and a clear lake (LV) isolated since the last glaciation. The questions we asked were: (1) Are there differential adaptations of the eyes and the retinal photoreceptors to the different light conditions in the two lakes? (2) May mutual visual detection in some of the possible predator-prey pairs be significantly shifted by brownification? We found no differences in eye optics, photoreceptor complements, or the absorption spectra of the visual pigments between the LT and LV populations of any of the species. However, there are clear differences between the species in how well they are predicted to manage in the different light environments. For example, the pikeperch eye "favours" high sensitivity (reflecting tapetum, shorter focal distance), in contrast to the pike eye, which (by comparison) "favours" higher acuity at the expense of sensitivity (longer focal distance, no tapetum, yellow cornea). Modelling the visibility of each species in the eyes of the others we also found that the perch enjoys a relative camouflage advantage in dark brown water due to its high surface reflectance at long wavelengths.