How Long ?

[NottsFishy]

How long can fish survive without light ??

I have a syno that only comes out at night and my common plec prefers darkness but what about fish that are mostly active during daylight ??

 

[Colin_T]

Indefinitely. Fish can live in tanks without light all their lives. We have lights on the tank for plants, corals and so we can see the fish. Average room light is sufficient for most fish.
Catfish are nocturnal and spend most of their day hiding only to come out after dark.
You can use night lights (blue lights) at night and this allows you to see your nocturnal fish but the light doesn't upset them.

 

[Captain Retardo]

Yes, Colin T is correct, this november I went to mexico for 2 weeks and I left the lights off, fish were fine afterward