From what I've seen, yes, after a while--probably once they've adjusted to the lighting. Generally I try to move them up slowly. I've had them speckle when moved from a tank with PC to the bottom of a tank lit by T-5's, so not much I could do to move them lower, so they just had to adjust. I wouldn't try to put them up near a MH bulb, though, and expect them to just "deal".