Do fish need light?

[madly99]

Are there any reasons why fish alone need the tank lights? Since I removed the live plants in my tank, I've been keeping the lights off in my tank when I'm not home, in hopes I might prevent algae and to keep the tank temperature down.

The tank is in a bright room with windows and a skylight, though none of the light hits the tank directly and it's certainly not as bright in the tank as when the lights are on, but the fish are easily visible. I usually just turn the light on from when it's too dark to see them until I go to bed, and sometimes I'll turn it on during the day to feed them just to make sure they catch all the food bits.

Thoughts? Thanks!

[AquaQueen]

Well I only put the light in all of my tanks on when it gets dark outside until bed time. I try not to ever put it on during the day because my whole house is well lit from the sunlight so I can see them just fine, and also to prevent algae. It sounds like you are doing just fine as far as lighting goes.

[Nick_Pavlovski]

What sort of fish are they?

Letting direct sunlight fall on the tank is bad because of the green algae growth that results, not because it'll hurt the fish.

From a thread earlier this year, most people have their lights on no more than 12 hours a day.
Is your light particularly bright? If so, maybe a lower strength bulb/tube is needed.

The light won't affect the tank temperature much, unless it's a very strong light and a tiny tank. Ambient room temperature will affect the tank more.

I hope this helps? Keep asking if not...

[Spyder]

In an unplanted tank lights are for you, not the fish. They don't need lights as long as room light is decent.

[AquaQueen]

Letting direct sunlight fall on the tank is bad because of the green algae growth that results, not because it'll hurt the fish.


This is so true...I learned the hard way. I had one of my tanks in front of a window for a few months and constantly had to battle algae, I thought where there was a back on the tank that would help with the sunlight but nope didn't change anything. I ended up moving the tank and that finally fixed it, no more algae ever since.

[madly99]

To answer Nick's question - they're just two tetras and a danio - nothing particularly exotic. I was just thinking along the lines of people needing vitamin D and natural light, etc., and wasn't sure if fish had similar requirements.

Thanks all!