Instructions
Read your light fixture's manual. Get to know the details of your aquarium lights, especially where the switch is located.
Determine how the long the aquarium has been lighted to see if it is time to turn the lights off. Keep a regular schedule that will track when you will turn the aquarium lights on. This will ensure that your fish have a regular day and night cycle. Keep the lights on for 12 hours and keep them shut for the next 12.
Locate the switch of your light fixture and turn the lights off.
How to Turn the Light Off at Night for a Fish Tank
Artificial lighting is used in fish tanks to mimic the natural day and night cycle of fish in the wild. Unfortunately, some people may neglect to turn off the lights of their fish tank. This can throw off the fishes' natural body clock, as they are unable to distinguish between day and night. This may cause unnecessary stress upon them and may contribute to their declining health.