Since lion already point out they do not go asexual. I would personally leave the lights on the fuge while the main tank light is off. I set mine on a timer, 12:30pm-12:30am main tank lights on, 12:30am-12:30pm fuge lights on. I have the opposite light cycle, it is also recommanded to leave the fuge lights on 24/7 Is there anyway you can place the fuge somewhere hidden so not much lights would show?? I have mine under the cabinet, the tank is located right next to my bed. I'm used to the low dim lights that comes out from the back of the tank....If you choose to leave it off, that is fine as well.... :happyfish