Are fish sensitive to day/night light cycles?

Do you think that day/night cycles are important to fish??.... is it cruel to leave the lights on in a fishroom during the night??…..


Currently… I leave the lights on 24/7, as… in past experience… I have lost more fry and/or eggs being eaten by the parents during the period that I switched off after dark and then switch back on in the mornings…. I assume that their (Cichlid’s and Bubble nest builders) inability to fan and mouth the eggs during the darkness hours must have something to do with it, but… how do they do it in nature then??


On the other hand…. when spawning egg scatterers… I find that putting males and females together just before lights out…. they spawn much more readily in the mornings about 30 minutes after the lights are switched on than they would if the lights remained on…..


What would your advice be… leave the light on at night…. or switch it off??... (I’m talking fishroom here… and not display tank)….

 

Hi oom Cheetah

What i know about this, is that yes it is important to them, fish room or display tank.

Fish does go into a state of sleep, or where they shut down just like humans. If lights was off and you suddenoy had to put them on, you can clearly see it by loss of colour and them being not active.

Leaving light on will put stress on your fish with out any doubt in my mind. And as you mention about the spawning part with lights off and on, same with weather changes and water changes that trigers spawning. They can feel the difference jyst like day and night.

So yes i woyld say, gice them some lights off.

 

I've been thinking of starting an experiment with dimming lights on a timer for my next tank.I'm not sure how well this will work on a planted tank though,i've been thinking of letting the lights start of very very dim and then work up to full power within 2 hours (the same for when it's time for lights off,except in reverse)

 

100% - 24/7 lighting is no good! My breeding rooms runs on zero artificial lighting. Lunar phases are just as important to some fish.

 

Hi guys. Very interesting question. I have to agree here. I think leaving the lights on 24 hours may become a problem. To answer your question about the eggs and babies getting eaten at night. I have also found this behavior.

In the wild because of the large rivers the fish will move on after babies are born so this may be the case.

 

@Reedfish yes allot of the pro breeders leaves a slight light on, this helps the fry to find the parents, and also boosts growth as they eat more often. Cause its such a dim light, it doesnt really effect them as mush as keeping full light on the whole day.