How Long Will A Fish Survive In The Dark

[aitchvee]

just think about some of those cave species of fish, they go their whole life without any light.

Kind of a moot point; I'm sure it's not a filter dweller!

 

[andywg]

I think you will find that many fish can absorb Vitamin D from their food. I seem to recall reading (though no doubt someone can correct me) that humans actually only need a few hours a year of sunlight (good for me at the time as I worked nights).

CFC's fish probably come out in light about once a year or so and are then fine, though they may absorb all the Vitamin D they need from their food.

 

[afishdude]

I think you will find that many fish can absorb Vitamin D from their food. I seem to recall reading (though no doubt someone can correct me) that humans actually only need a few hours a year of sunlight (good for me at the time as I worked nights).

actually i remember reading something like that in school a couple of years ago... i think it was like 10 hrs of direct sunlight per year or year and a half. but not 100% on that as my memory can be fuzzy sometimes.

 

[pica_nuttalli]

I think you will find that many fish can absorb Vitamin D from their food. I seem to recall reading (though no doubt someone can correct me) that humans actually only need a few hours a year of sunlight (good for me at the time as I worked nights).

CFC's fish probably come out in light about once a year or so and are then fine, though they may absorb all the Vitamin D they need from their food.

According to my nutrition books, fair-skinned folks only need about 15 minutes of sunshine on their bare arms to get their daily recommended dose of Vit D; darker people need a bit longer. (Vitamin D is important because it helps your body absorb calcium; by the way, caffeine helps deplete calcium so take your Ca+D pills with that soda!)

CFC is right that it isn't the actual lighting that it's important because any UV would be filtered out by the hood before it could reach the fish (not that common fluorescents produce UV anyways). The need for a day-night cycle is more psychological than anything, since it helps trigger natural diurnal/nocturnal behavior.

Your fish will be healthiest if they get several hours of "light" everyday. But a pleco (nocturnal, cave-dwelling fish) is not going to die because he's been hiding in your sump.

 

[Tommy Gun]

I agree with the notion that fish can live for quite a while without light...a pleco is probably one of the better examples of a highly nocturnal fish (well, some of them anyways, mine are not anymore), but I agree completely with CFC...there are tons of fish which never see the light of day and do fine. Deep sea fish would be one good example, but for a good freshwater example, think about the cave tetra - they seem to have liitle or no skin/scale pigment (like an albino) and have done away with the need for eyes!

^A short video of cave tetras I took during a recent trip to the Shedd Aquarium in Chicago, Ill.

 

[fry_lover]

mostly, fish need a day-night cycle for optimal health. thus leaving the lights on all the time is not good for them either.

indirect lighting is good enough for the most part, but it's better to have *some* direct lighting.

who say's?

has this been established?

if it has fine, i'd be interested, you speak like it definitly has, just curious

EDIT: i have bolded the parts i am interested in, especially your comment "mostly, fish need a day-night cycle for optimal health"

EDIT AGAIN: there's a get out clause i guess in terms of "mostly , fish need a day-night cycle for optimal health"

 

[BNyleen581]

It depends on the fish.

Yes, a day and night cycle is beneficial for most Freshwater fish.

Again, it depends on the fish, (whether they need light or not) some are from caves, some from tropics, some from mountains... Not all fish are green so why would we asume all fish are green, (just an example here).

This isn't hard people.