To Light Or Not To Light

[Alz1992]

Currently my 20g tank has no light. that doesnt bother me in the slightest but family members decided "ooooh it'd look better with a light, lets price one up ".
my question is, would it annoy/stress my fish if i were to get one? my logic is:

without a light, the tank naturally gets lighter during the day, and darker during the night, reaching a peak at midday.
with a light, the tank will get a sudden strong burst of light in the morning which persists all the way up to anywhere between 10pm-12am before its suddenly switched off.

i'd have thought it'd be more natural and better towards the fish if i went without a light. also it wouldnt interfere with my heating.

opinions?

(Tank stock is 1 albino cory (adding more friends for him, maybe 4 more, he was liberated from the LFS) 3 black phantoms, and a betta)

 

[electropunk06]

Hi my fish don't seem to mind the light going on and off in the slightest. IMO having lights dose look better also you can grow plants, but you may get some algea.
What shape/size tank do you have?

 

[Alz1992]

its a tall rectangular 24" by 12" by 18"

 

[Lufbramatt]

It shouldnt interfere with your heating as the thermostat on your heater will simply turn off the element as the water heats up. Flourescent tubes give off little heat anyway and will have minimal effect on the water temp.

I have my lights on a timer so they come on at 5:30pm and go off at 10:30pm, basically they're only on while i'm around after work. Just enough to give my plants (java fern and vallis) enough light to photosynthesise. IMO tanks look so much nicer with a few real plants which is the best reason to put some proper lighting on the tank. The bulbs are staggered by 15 mins so the fish dont get so much of a shock.

I also notice a distinct change in behavior when the lights come on- the fish seem more aware of their surroundings and each other. They also know that its food time when the lights come on and come to the front of the tank When the lights go off they are much shyer and stay close to their shells, and their colours get more drab.

 

[Kaybear11]

I used to have some fish that would jump when the lights were switched on or off. I decided to try giving them a "sunrise" and "sunset". When I decided it was time for them to start waking up I would turn on the room light, let them get used to that for a little while and then turn on the tank light. Same for night, I would turn on the room light, switch off the tank light, give them a little while and then turn off the room light. They were no longer spooked or stressed after I started that process. Yea, may be a bit excessive but I do stuff like that for my fish if something bothers them

 

[Hoppo]

I have noticed that my cories only feed when the light is off.