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View Full Version : How Much Light Should My Fish Get?


robertprice
May 20th, 2010, 05:22 PM
At the May Meeting of BAS, as I was purchasing algae cure, I had some discussion at the table about how much light Tropical fish need. I mentioned that mine get 10-12 hours a day, as that is what wild ones get in the tropics. A wee known member disagreed with me and maintained that 5 is enough. It is certainly not. Virtually every reference online agrees with me. The lowest I could find was at least 8 hours. This is a vital piece of information, especially for beginning aquarists.

alazandv
May 21st, 2010, 10:30 AM
At the May Meeting of BAS, as I was purchasing algae cure, I had some discussion at the table about how much light Tropical fish need. I mentioned that mine get 10-12 hours a day, as that is what wild ones get in the tropics. A wee known member disagreed with me and maintained that 5 is enough. It is certainly not. Virtually every reference online agrees with me. The lowest I could find was at least 8 hours. This is a vital piece of information, especially for beginning aquarists.


Reading your post I tend to agree with the guy that said 5 hours are enough especially when taking into consideration the fact that you are battling an alrgae problem as stated by your post. There is certainly no standard as to how much light your fish "need" per day. Unless you keep your fish in pitch-black basement, some light is required to allow the fish to differentiate between day and night cycles. If your tank is located in the bedroom, hallway or living room that has windows and yours is a fish only setup the fish themselves do not require any more light then there already is coming though the windows. The daylight, both in its quality and quantity is more the sufficient for a fish-only setup.

It is actually not natural to have a fluorescent bulb over your fish for 10-12 hours a day. The fish found in the hobby come from all sorts of places on earth. Some come from areas where there is a lot of light and most actually come from places well hidden from the sun rays. Unlike lizards, plants or corals, fish don't need to bask in the sun for extended periods of time.

It is us, human beings, that decided to put a bright light fixture over fish tanks to make them more pleasing to the eye. The light is what makes the colors "pop" and "highlights" our aquatic creations in our homes.

Assuming you still have your alae problem and you don't have live plants I recommend multiple water changes along with drastic cuts in light exposure. Many individuals on other online fora even cover their plantless tanks with dark fabric to starve the algae. I also recommend you "skip meals" for your fish and when feeding do so sparingly. Overfeeding and poor husbandry techniques are major causes of algae blooms. The best way to remove algae is to remove its root causes. Hope this helps.

robertprice
May 21st, 2010, 02:22 PM
Thanks for the info. It's still wrong, and by the way I'm a Ph.D Zoologist with at least as much experience as you have and probably a lot more. Why don't you Google "How Much Light do Tropical Fish Need?" if you don't believe me. I also did not stipulate where the light came from, or what intensity it has to be.I never said the light had to come from an artifical source. Tanks in south facing windows can get that much light without any bulb. Ott Lite and other bulbs reduce the fluorecent intensity and frequencies to an indoor type light. I assume you didn't think I was advocating 10 hours of light for Blind Cave Fish, either. I don't have an algae problem. Some Algae is healthy and it is certainly natural. (It really does grow in the tropics.) I occasionally use algae products and I have very aggressive fish who do not want implements intruding into their territory. You should have taken one of my courses in Aquaculture or Ichthyology. I wound not have been very tolerant of your spelling either. No hostility intended, but wrong is still wrong.

xoomer
May 24th, 2010, 05:20 PM
I didn't know that misspelling anything disqualifies one from posting on this forum. We try to keep this forum open to comments and suggestions and you certainly don't welcome any Dr. Price. For somebody who is looking for algaecide, you sure sound convincing that you don't have an algae problem. Up until now, you still haven't stated whether your tanks are full of live plants (that do indeed need light). You still haven't stated the type of fixture you have over your tanks for anybody to suggest anything. Please list your current setup and you'll see what people recommend, this is an open forum and everyone is entitled to an opinion.

As to no hostility intended statement above I'll respond with the following question. Why would you ask how much light is required if your mind is already set on your own number? Were you looking too seeing if everybody agrees with you or were you just looking to start an argument? Please, lets keep it friendly and be open minded to allow for healthy discussion of topic at hand. Thank you.

robertprice
May 25th, 2010, 04:32 AM
Okay. Let's put this issue to rest, Firstly I don't have an algae problem. I may go through 1/2 bottle a year in my Flowerhorn tanks.The question I asked was entirely casual; I wanted to know what the vendor's opibion was I should digress here to point out that fish have day and night related biorythms, just like people. Too much lght and they will not get enough rest. Too much night and they tend to become listless, lose their color, and bevelop a number of problems that effect their health.I did say 10-12 hours of light a day for Tropical Fish Tanks. This means sweet water tanks over 72 degrees with fish in them that come from Texas and Florida on south. Ceertainly there are exceptions but I wasn't referring to those. Without being overly specific about light intensity,a brands, and strange fish, the following sources agree with me that 10-12 hours is neeeded for the average fishtank. Yahoo (2 citations), Fishlore.com (3 citations), and Tropical Fish Center. Ifyou give your standard community fish only 5 hours of light a day, they will not thrive. I don't care if Zeus comes down from Olympus and says otherwise.

Occidentalis
May 25th, 2010, 10:56 AM
Robert

While I agree with you about the lighting photoperiod, weak ambient light still counts. Running the main lights five hours a day may be sufficient if the animals are also receiving ambient room lighting for the rest of the photoperiod, and complete darkness at night. That's most likely where problems are going to occur - complete darkness is hard to achieve, even in nature. Many animals seek out cover at night, not only for predatory protection, but from weak star light that can throw off their circadian rhythms.

The amusing thing is, they are most affected by the wavelengths emitted by blue LED's - exactly the type hobbyists consider "moon lighting." There is considerable evidence that this is detrimental to nighttime melatonin production. See: http://www.sciencemag.org/cgi/content/abstract/183/4128/970 (http://informahealthcare.com/doi/abs/10.3109/07420529209064541) and http://informahealthcare.com/doi/abs/10.3109/07420529209064541 (http://www.sciencemag.org/cgi/content/abstract/183/4128/970) for more on that.

Yahoo (2 citations), Fishlore.com (3 citations), and Tropical Fish Center

Cmon man, you know you can't get away with citations like that =P

Take care
Alex