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Do Fish need any Light?
http://byap.backyardmagazines.com/forum/viewtopic.php?f=2&t=22045		 Page 1 of 1
Author:  bits45 [ Jun 13th, '14, 11:32 ]
Post subject:  Do Fish need any Light?
I'm new to aquaponics and new to this great BYAP site.

Before I finalize my system and introduce fish (currently cycling and finishing up construction details), do fish (gold fish to start with) need any light at all to thrive?

I've seen many systems with covers. I also plan to have different layers of insulators as the weather changes here in Augusta, Georgia, USA.

Does anyone have advise on leaving any indirect light for fish? I currently have white corrugated PVC panels covering my sump and fish tanks (solid black Rubbermaid), but also have plans for thing insulator boards to cover the tanks themselves as weather dictates.

Thanks for any input on this subject? I'll keep trying to search these forums for any other posts.

Cheers,

Bits
New Member: viewtopic.php?f=45&t=22018
Author:  Yavimaya [ Jun 13th, '14, 11:37 ]
Post subject:  Re: Do Fish need any Light?
People put covers on to stop algae growth, etc.

I think the simplest way to answer this would be to say.... Do your children need light to thrive? wosuld you keep your children in total darkness and think they will grow up healthy?

Dont forget fish didnt evolve in the dark.. they live is the same world as us.

Im a proponent of allowing as much light (with shade too) into a tank as possible - of coarse this is once well established, i have never seen an established system have an algae bloom problem, only at the start before it is all working properly.
Author:  mattyoga [ Jun 13th, '14, 11:40 ]
Post subject:  Re: Do Fish need any Light?
An issue with having the tank really dark is that when you open it to feed etc, the fish will generally go to the back and hide. If there is always a bit of light they are generally better at coming up to eat so you get a much clearer feed response and you can observe your fish easier.

I have shadecloth with an opening at the front to let light in.
Author:  bits45 [ Jun 14th, '14, 00:14 ]
Post subject:  Re: Do Fish need any Light?
Thanks guys for the input. I appreciate it. I hadn't seen anyone ask this before, but I saw some pretty "complete" covers on other systems in videos and images.

Take care.

bits
Author:  Ronmaggi [ Jun 14th, '14, 00:41 ]
Post subject:  Re: Do Fish need any Light?
The previous answers are correct to some degree, but fish do like it dark. Light to them means danger of predators. And yes, some fish did evolve in the dark. Quite a few in fact. Your fish will make the association with light meaning food before long, and the problem with them hiding will go away.
Author:  Yavimaya [ Jun 14th, '14, 07:43 ]
Post subject:  Re: Do Fish need any Light?
yea some did Ron, but who here keeps deep sea or aquifer fish in thier AP systems? no one, im sure.
they like shade and places to hide, "dark" is totally different.
Author:  Azira [ Jun 14th, '14, 08:13 ]
Post subject:  Re: Do Fish need any Light?
It was a while ago now, but I do remember when I was looking into lures and water+light conditions etc, that depending on the water quality light really didn't penetrate very far down into the water column at all. In clear ocean water it was further down, something like typically to 200metres, but in other waters the light penetration was greatly reduced, muddy waters it was only a couple of metres at best.

So it's possible that given that a fair amount of fish do tend to hide in darker water, underneath structures and so on, that a dark tank would be better to keep them calmer and more relaxed. But that being said, whether or not they actually require light I'm not sure of. I know when fishing the only fish I've ever seen hanging out in direct sunlight were large carp, and sunlight does have an effect on the colour of Koi, but I don't think they actually absorb vitamin D like we do which you'd assume would be the main be benefit of sunlight, they get it from their food source. In ponds and so on, I have noticed that if there are any dark spots or if the water is murky, they will choose to hide rather than be exposed.

I'm really just thinking out loud and rambling, personally I don't think having a dark tank is going to harm the fish in it and chances are it won't be in complete darkness 100% of the time anyway (feeding and so on).
Author:  Yavimaya [ Jun 14th, '14, 08:32 ]
Post subject:  Re: Do Fish need any Light?
No one is doing ocean fish in AP, so those are irrelevant, even in the murkiest australian rivers enough light penetrates for the fish to get thier dose of Vitamin D, As far as fish health goes i think that the ability to get atleast diffused light is very important. What makes you believe that fish dont absorb vitamin D like us? Why do so many people think that animals we evolved from basically are going to work in a totally opposite way to us biologically?
Even when hiding in shade under a branch, etc in muddy water the fish have enough light to see thier prey, to avoid obstacles, etc. They are not in the dark.

A shade cloth cover might not be a bad idea at all, but there is a fish farm that i have bought fish from, it is in a shed, he has old weak flouros hanging about 3+ metres above tanks that are completely in the dark - plastic covers and he still said to me "i think i have too much light in here". WTF??

The best example i can give is look up "rainbow fish", ones grown up in aquaria are almost colourless, they are plain and sickly looking, those grown in ponds/dams are colourful and have a nice sparkly sheen in certain light - they are an australian/ new guinea native fish, They are meant to be colourful when healthy.
Author:  Stuart Chignell [ Jun 14th, '14, 08:38 ]
Post subject:  Re: Do Fish need any Light?
I don't know about fish in general but I do know about trout.

Trout are primarily sight feeders so they need light to see to find there food (mostly).

Also trout have been found to grow better with increased light levels.

In one study "Effects of Different Photoperiod Regimes on Growth and Feed Conversion Rate
of Young Iranian and French Rainbow Trout" by Barimani, S. et al 2013.

Quote:
Abstract: To determine whether the French and Iranian rainbow trout (Oncorhynchus mykiss) will show
different responses to the different photoperiod regimes or not, fish were kept under four photoperiod
(light:dark, L:D) cycles (24L:0D, 16L:8D, 12L:12D, 16D:8L), for 60 days. The results of this study showed that
in French rainbow trout with 45.14±0.72 g initial weight, weight gain was higher in the (24L:0D) photoperiod,
but did not significantly differ from the (16L:8D) photoperiod (p>0.05). Specific growth rate (SGR), was
significantly higher in the (24L:0D) photoperiod, than other treatments. Condition factor (CF) in (24L:0D)
photoperiod, was higher than other treatments but did not significantly differ from the (16L:8D) and (12L:12D)
photoperiods. The feed conversion rate in the (24L:0D) photoperiod, was significantly lower than other
treatments. In the Iranian rainbow trout with 46.02±0.6 g initial weight, weight gain in the long photoperiod
(16L:8D), was significantly higher than other treatments. Specific growth rate and condition factor were higher
in the long photoperiod (16L:8D), than other treatments but did not significantly differ from the other treatments
(p>0.05). Feed conversion rate in the long photoperiod (16L:8D), was significantly lower than other treatments.
Survival in both experiments was not affected by photoperiod manipulation. For higher growth and lower feed
conversion rate, the continuous (24L:0D) and the long photoperiod (16L:8D) are recommended respectively for
young French and Iranian rainbow trout.
Author:  Azira [ Jun 14th, '14, 09:32 ]
Post subject:  Re: Do Fish need any Light?
Yavimaya wrote:
No one is doing ocean fish in AP, so those are irrelevant, even in the murkiest australian rivers enough light penetrates for the fish to get thier dose of Vitamin D, As far as fish health goes i think that the ability to get atleast diffused light is very important. What makes you believe that fish dont absorb vitamin D like us? Why do so many people think that animals we evolved from basically are going to work in a totally opposite way to us biologically?
Even when hiding in shade under a branch, etc in muddy water the fish have enough light to see thier prey, to avoid obstacles, etc. They are not in the dark.

A shade cloth cover might not be a bad idea at all, but there is a fish farm that i have bought fish from, it is in a shed, he has old weak flouros hanging about 3+ metres above tanks that are completely in the dark - plastic covers and he still said to me "i think i have too much light in here". WTF??

The best example i can give is look up "rainbow fish", ones grown up in aquaria are almost colourless, they are plain and sickly looking, those grown in ponds/dams are colourful and have a nice sparkly sheen in certain light - they are an australian/ new guinea native fish, They are meant to be colourful when healthy.

You have to take what I say with a grain of salt, it was a while ago now I was looking and can't remember exact specifics, let alone the actual accuracy of what I read.

When I was looking my focus was mainly freshwater as that's what I was fishing, specifically murky, muddy water as that's where I was spending most of my time. After a metre or two the majority of the available spectrum of light was gone, mostly only shadows being seen or something. But either way, still not totally relevant to AP.

I'm not totally sure about the vitamin D thing either, like I said, take it with a grain of salt. Like I said about the Koi and sunlight, they are a prime example of how the light changes their colouring, it intensifies the colour a lot to the extent that too much can apparently cause them to get a 'tan' of sorts.

Hmm, not sure, I'm just rambling again!
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