They are night walkers. IF you have a reef tank, about 1 to 2 hours after the lights go out, look at all your corals and inverts. Most corals make a transitional look from day to night and extend the polyps out to catch free swimming food. You can also take a flash light to the top of the water after the hours are out for a while and see all the zooplankton thats live, swim to the light. And your coral banded will be crawling around at night.