Young-of-the-year Bear Lake sculpinCottus extensusfeed throughout the day on benthic invertebrates and cease feeding at night when they migrate to the metalimnion. We investigated their reliance on vision by conducting feeding trials at different light levels in the laboratory. Feeding rate reached a maximum at intermediate light levels (near 1016photons·m−2·s−1; approximately 1 lux) but decreased as light intensity increased beyond this range. At this maximum rate, the fish fed nine times faster than they were able to feed in the dark, showing that young Bear Lake sculpin rely heavily upon vision to feed. The light intensity at which feeding was greatest corresponded to intensities found on the bottom of Bear Lake (40–60 m) during the day.