Do fish need light?

ambient room light in most instances is enough light for the fish to receive appropriate nutrients. (yes there are some exceptions we can all think about and create for sake of arguement).

tank lights are usually flourescents--not the same as the sun. the fish do not get what they need from "electrical lighting". they need at least indirect sun light. Light is typically the last issue causing problems. think about our own issues with vitamin d in the winter months--simple distance from sun in winter stops us from getting as much as we need. plenty of "sun light". just not close enough. many similarities with fish.

The lights that come with tanks are really so hobbyists can enjoy the fish. not really doing anything for the fish themselves.
 
its not the source of the light that matters, its the spectrum. why do you think plants can grow under flourecent lights? its not sunlight, but they still grow happily. i use a flourecent daylight bulb over my plants since my windows are all east facing and about 4 feet away from a 2 story building.
 
Yes. You are right. I tried to avoid a long answer in the middle of the night.

The light required to do any good at all in a fish tank is “full spectrum light”. Vitamin D is one of the key vitamins received as a consequence of the middle range of ultra violet radiation.

The bulbs frequently utilized by hobbyists, without planted tanks are, however, the common fluorescent tube. These supply little if any of the mid range ultra violets essential fro the generation of D3. “Day light” tubes have a better balance of the various bands of the light spectrum. If the hobbyist feels the need to supplement ambient light then he/she would want to use bulbs with a CRI>88 (CRI=Color Rendering Index). They are most like mid day sun. Basically the bulbs should be at least 5,000 K. 6500 K is maybe better (this range is often used for judging accuracy of color replication in the graphic arts world).

The only statements I ever found referencing light and fish say that fish require a minimum of 6 hours a day of sun like light. At the same time some of the sites state that “5 watts per gallon” is a minimum required to facilitate the benefit of “day light”. That would be a lot of light (I periodically plug that level of light in for a planted tank—but rarely leave it at that intensity for long (only when I kick up CO2 and fertilizers to generate a bit more rapid growth).

I cannot say that I cannot say with any scientific certainty what the minimum time required, or minimum watts per gallon required are. I can use experience dating back over 25 years when I started keeping fish. I can also make use of anecdotal information from hobbyists I have known and trusted as well as hobbyists I have met online. And, I can go back into history, when royalty kept tanks without heat, light or the type of filtration we utilize.

I have kept tanks for many years that had no supplemental light. They got the ambient room light during the day (or useless fluorescent and incandescent light). The life spans and the fecundity of the fish were no different than of fish kept in “lighted” tanks.
Breeding activity occurred. Growth occurred. And the fish lived as long (or longer) than the “average number of years bandied about as what we should expect.

Maybe this should be a topic for doctoral research as well. Why don’t more people do more “scientific” research into fish? Until they do, however, I guess the best I can go by, in an instance like this, is what has worked or not worked. I guess it is taking advantage of the “body of knowledge”. Without really knowing its source.
 
Sully said:
Maybe this should be a topic for doctoral research as well. Why don’t more people do more “scientific” research into fish?
Click to expand...

Haha, funny you should say that. Ever since I got into this fershluggner hobby, I've been trying to cook up ways I can do my thesis on aquarium fish so that I'll have an excuse to buy lots of tanks and spend all my time fawning over their inhabitants. :dive2:
 
Personally, I'd give the fish at least 8 hrs of light every day. Put the lights on a timer and never have to worry about it.
 
Fish, unlike mammals, birds and reptiles, do not respond to sunlight and rely on vitamin D found in phytoplankton and other fish. Salmon must feed on phytoplankton and fish in order to obtain and store significant vitamin D in their fat, flesh, skin, and organs.

Ahhh, don't compare fish to humans as far as Vitamin D is concerned.

As for a daily cycle being a good thing. Well since the fish we keep are from relatively shallow waters then they are used to some form of light, though what sort of level would be debatable since water filters light and what ever is in the water can filter it more.

Will fish loose their eyes without light? No, but poor living conditions could make that happen.

Oh and farm raised fish is a poor source of Vitamin D for people. This is due to diet. Wild caught fish is still a great source of vitamin D. Yet, both get light.

Lots of ponder. And so easy to do without personal attacks. Hmmmmmmmm
 
Thanks TKOS, for a very thoughtful post!

What you have just explained is what I was getting at before the personal attacks started. I started to type a lengthy reply (which wouldn't have been as well stated as yours by the way), but I was a bit upset with the tone of certain posts and wasn't clear-headed at the time.
 
It is easy to get upset when the person you are talking to (writing to) isn't there, but eventually the brain will kick in and remind us what we are here for. Perhaps Vit D helps with that? More sunlight for me!!!
 
The RML (Rainbow Mailing List) advocates keeping rainbows near windows so that they can get at least an hour of sunight a day directly on the tank.

Apparently, and I've yet to test this claim because I do not have enough window access, bows like to bask in the sun and will swim in only the sunlit areas of the tank during that period of the day.

Quite a few of them do this and I believe them.

Also, many Australian keepers pond their rainbows and have reported they are healthier, bigger and more long-lived.

Food for thought.

Roan
 
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