# How long can fish last without light?



## AquaNeko (Jul 26, 2009)

How long can fish last without light?

If I needed to turn off the lights for say 2-3 weeks or so will it be ok? I'm turning the tank lights off but some room lights will be on as I'm in thwe room doing other stuff. What will happen tot he fish if the lights are off that long? 

Will they become vampires?


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## characinfan (Dec 24, 2008)

Their ability to read will be diminished but otherwise they will be fine.

(If they normally nibble on plants/algae in the tank, they might need extra veggies in their diet -- otherwise, no big deal).


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## Darkblade48 (Jan 28, 2008)

They should be fine, as mentioned.


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## AquaNeko (Jul 26, 2009)

What if it's a total sealed in blackout to keep no light shining in? Also what is the longest time that will be ok? Say months or more?


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## gucci17 (Oct 11, 2007)

lol they'll be ok but why months of no light? That may be going a little too far...


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## Cory (May 2, 2008)

If they had no light at all they would eventually perish. Fish need light to see the same as we do and when the lights go out they go into a resting state which means they aren't eating. Light also provides fish with vitamins the same way it does us so while they'll be fine in your tank with low light while you are in the room, total darkness would be a bad idea. 

Out of curiosity, what is stopping you from using the lights for 3 weeks?


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## AquaNeko (Jul 26, 2009)

Cory said:


> If they had no light at all they would eventually perish. Fish need light to see the same as we do and when the lights go out they go into a resting state which means they aren't eating. Light also provides fish with vitamins the same way it does us so while they'll be fine in your tank with low light while you are in the room, total darkness would be a bad idea.
> 
> Out of curiosity, what is stopping you from using the lights for 3 weeks?


Algae control via blackout.


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## gucci17 (Oct 11, 2007)

I would like three full days of a total blackout would be sufficient for a algae blackout. Even one week is alot...just cover your tank(s) with something opaque so no light gets in for those few days.


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## Chris S (Dec 19, 2007)

As mentioned, no need to do a blackout for 2-3 weeks for algae control. 2-3 days will suffice.


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## KhuliLoachFan (Mar 8, 2008)

2-3 days will suffice, and any more than that won't kill anything that wasn't gonna die in 3 days. Your fish will be find even in a 1 week total blackout it's just not very kind.

W


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