Can fish sleep with room light on?
Mia Lopez
Updated on February 16, 2026
Aquarium fish do not need light and it is best that you turn it off during the night. Leaving the light on can cause stress to fish as they need a period of darkness to sleep. Too much light will cause algae to rapidly grow and make your tank look dirty.
Is room light enough for fish?
Yes, aquarium fish need light to determine whether it's day or night. However, the natural light in your room is sufficient. Fish do not necessarily need an extra aquarium light. An aquarium light is to see your fish, and for live aquatic plant photosynthesis.Is it okay for fish to be in the dark?
Fish Lighting RequirementsHowever, most fish require around 12 hours of light a day. Fish such as goldfish will lose their color without light, and some fish may stop eating, become lethargic or become ill without sufficient lighting.