Juvenile smallmouth bass showed a marked response of utilizing opaque plastic coverts in a stream aquarium with two water velocities (12 and 28 cm/sec). The most complex of six opaque coverts at the higher water velocity was occupied a mean time of 7190 ± 6 out of 7200 sec. The presence of a visual reference point was the first feature to attract a fish to a covert for a marked period of time. The addition of an area of darkness increased the use of a covert. Maximum use was obtained with the above features plus an area of quiet water. Clear plastic coverts, which supplied only thigmotactic stimuli or thigmotactic stimuli and an area of quiet water, were rarely used.