How important is lighting?

[VulcanNinja]

I'm wondering if people leave their tank lights on too much. I've been dealing with algae, and I have my tank lights on about 10 hours a day. I just cut it back to 9 hours. Anyway, I guess I'm asking if it even matters if a tank is lit or not. How do the fish react to the light?

 

[Barday]

It's important if you have live plants in your tank, If not 8h of light will be fine

 

[glolite]

Agree with above and I'm pretty sure that fish need light to stimulate them to feed.

 

[CFC]

If the tank has no live plants then just the light from the room is enough to let the fish know it is day/night. To keep costs down my breeding/fry rearing tanks and my quarentine/grow out tank do not have lights on them and this does not affect the fish.
If you have a unplanted set up then the best way to keep algea growth down is to only have the lights on during the hours you want to view the fish, if you work a normal 9 till 5 job then set the lights on a timer so that they come on at 5.30 in the evening and go off when you usually go to bed.