English: Example of adult zebrafish optokinetic response behavior to a rotating drum of black and white stripes in the two lighting conditions used in these experiments. In visible green light, the fish demonstrates robust optokinetic motor response to an opkinetic drum stimulus, aligning so as to swim in opposition to the perceived motion of the visual surround. In darkness with infrared illumination, the fish appears to be unaware of the rotating vertical stripes, thus confirming poor visual acuity under infrared-only lighting.