moonlight lighting any use/good?

[alleykat]

Hi everybody,

who has any experience with moonlight lighting in freshwater tanks? I saw a relatively cheap (40 euros) unit in a shop, and it seems a nice way of seeing a bit more of my l239's just after lights out. The shopowner claims that 'fish can't perceive the light', (which, curiously enough, can be bought in red and blue) and are therefore not disturbed by it. It seems almost too good to be true. Any opinions/experiences?
Thanks!

Alleykat

[2wheelsx2]

That guy is selling you a line. I've had blue and white moonlights and the fish don't care what colour it is. I don't like the blue moonlights as it's not natural viewing. Very dim white LED's work well for that purpose. The fish still come out but the colours are natural.

[Narelle]

Fish (or at least marine fish) are unable to see the color red because red wavelengths penetrate the water the least, so there is no reason for them to have the ability to see a color that basically doesn't exist in their world. (It's is why there are so many red marine fish. It makes them less visible to predators, making for very effective camouflage.) So red would probably go unnoticed to nocturnal fishes and make viewing them easier. But in my opinion, it is a bit hard to look at a red tank.
Blue is the color that penetrates the water the most, which is why the deeper divers get, the more blue everything looks. I don't know if blue "moonlights" would be dimmer to to fish or just contain less colors in the spectrum - I would guess the latter. It might at least give them a greater illusion of depth and, to bottom dwellers, security.
Blue moon lighting really doesn't make much sense for fish. I think it is just a visual effect for the benefit of onlooking people. We think of moonlight as being white or blue, and deep blue lighting looks dimmer to us, so that is our "night" lighting.

I do have LEDs that have blue "moonlights", but haven't really used them enough to see if they worked. Initial tries with my Pseudomystus didn't go over well - he still hid about as much as with the daylights on. And since I didn't buy a ramp timer to go with them, I would have to manually change my lights every day to keep it up.

[dpm1]

Its an old wives tale that fish no fish can see red. Simply looking at how many fish have it as their main or part of their colours and applying reasoning will soon dispelled the myth. (Note: Slighty edited to emphasise its not a clear yes/no divide).There are even fish that have alternate dark/night/stress patterns that remove the red colours which is the opposite that would be expected if this was supposed to make them invisible to predators - surely they would go more red!

And indeed if red is the perfect camouflage why does it seen to be shunned by predators? Surely if they could effectively be made invisible there would be evidence of at least one 'super predator' that was primary red as opposed to the usual black/grey/blue shade (note this is different to the sedentary ambush type predators who can be any colour to fit it with the surroundings).

Actually red makes fish stand out under red light as a 'shape' although it is very poor for discerning details. As such it is a very good night light light in freshwater tanks as the noxttunal types can make much more use of it than the myriad of day swimmers.

Conversely marines exhibit very different effects and blue works much better. Unlike in freshwater where the tank takes on a very sterile effect in the very different chemistry of salties it can bring out much detail, and is especially effective in systems with coral and critters who exhibit luminescence that make them look very different under short wavelengths.

Very dim white can also work in tanks to a lesser degree. Perhaps its not as effective at quickly drawing out true nocturnal types but has the advantage of allowing more detail to be seen.

[Narwhal72]

Sorry dpm but you are completely wrong on your premise.

Red wavelengths are attenuated by water within the first 3 feet. This is not someone's opinion. It's a measurable fact. The longer the wavelength, the faster it is attenuated with depth. Fish beyond 3' aren't seeing red. There is no red light to see. The reason there are so many red fish (especially as you go deeper in water) is because something that is colored red will fade into the background and become harder to see. This is a way to avoid predators or if you are a predator such as a Mineatus grouper you can sneak up on prey. If you have ever gone scuba diving with a divelight you will miss fish at depth that become very visible when you shine a light on them.

The chemistry of water does not change the look of light in water (although most freshwaters tend to be more turbid than a tropical coral reef). The corals and fish we keep in aquariums do tend to be from greater depths than the freshwater fish which is why you see so many more red marine fish than you do freshwater ones. It's also why corals react to ultraviolet light more as there is more blue and UV light at depth than the red end of the spectrum.

As far as a nightlight goes. It's the only time I ever get to see my wood cats and banjo cats move around. Otherwise they hide under leaves and in the sand all day.

[Marc van Arc]

who has any experience with moonlight lighting in freshwater tanks? I saw a relatively cheap (40 euros) unit in a shop, and it seems a nice way of seeing a bit more of my l239's just after lights out. The shopowner claims that 'fish can't perceive the light', (which, curiously enough, can be bought in red and blue) and are therefore not disturbed by it. It seems almost too good to be true. Any opinions/experiences?

I will not enter the discussion whether or not they can see the light; fact is that my auchenipterids aren't bothered by it. Another advantage is that my angels (Pterophyllum) are able to see them roaming around at night and thus are not frightened by whiskers and/or bodies in pitch black.
I leave the moonlight on during the night and I'm very pleased with the effect. I'm at least able to see my fishes doing their thing, while they have little knowledge of me watching them.
Colour preference is personal. I have the blue light, because imo it's the one which makes the tank look quiet and serene.
So wrt your question: recommended.

[dpm1]

Ok maybe not an 'old wives tale' but certainly a gross simplification.

Whilst its true red is attenuated quickly in water the fact is that very many freshwater fish live well within the range of such light waves and as such a simple generalisation that the colour can not be used as a visual sensory clue is flawed considering the number of species that utilise it as basic colouring, marking and even breeding colour. There is certainly no shortage of species that could be listed (Rainbowfish, numerous tetra s, cichlids, livebearers, catfish...)

There are also very many fish with red colours in saltwater reefs well within 10metres of so of the surface.

Why would these markings exist if it simply made the fish invisible? If predators/prey couldn't see them then neither would potential mates. Its a balancing act and you can't have both. None of these fish would carry such distinctive colours in order to hide in plain sight thanks to their invisiblity cloak, and then cavort in daylight advertising themselves

Recent discoveries have even revealed deep see fish that utilise red light in hunting prey
http://www.livescience.com/3903-deadly- ... ights.html
http://biolum.eemb.ucsb.edu/organism/dragon.html
Some of these fish may have not detect the red in the exact manor that surface dwelling creatures, but detect it they do.

[bekateen]

There is definitely red-color sensitivity among at least some fish. For a quick orientation, you might try a simple Google Scholar search using the search phrase fish "red light" vision. The link provided is limited to work done in the last 10 years.

The nice thing about these search terms is they also pick up articles about using red light to view fish, as opposed to simply finding articles about fish being able to see red light.

Cheers, Eric

[bekateen]

Question: If you have fish that do not display in red for various behaviors (mainly aggressive or reproductive, I imagine) and are not very sensitive to red colors, then I would guess that the color of your night light doesn't matter and the choice is up to you. But if your fish do use red as a visual signaling color, then can we predict that red is automatically a poor color choice for a night light?

1. If red is used for aggressive displays, then would that tend to anger the fish? (which is bad)
2. If red is used to signal reproductive readiness, would that help get mates in the mood? (which could be good or confusing)

Personally, I have only two hoods that have built-in blue LED moonlights. They are from the Deep Blue product line. They are low cost and the fluorescent fixtures have worked well for me, but honestly, I'm not impressed with the night lights for two reasons:

1. They have only one blue LED, which is not sufficient to really illuminate either tank, so the effect is that I can't see much; and
2. There is only a single on/off power switch: When the switch is "on," the daylight fluorescents are working, and when the switch is "off," the fluorescent is off but the LED stays on. The problem with this is that I use a timer to control the photoperiod, so it cuts off power to the entire hood, turning off both the fluorescent and the LED at the same time. If I use the timer, I can't use the night light. This brand is incompatible with a power-supply based timer device, and should really have separate power feeds for the two light systems built in the hood, or it should have a built-in timer that turns off the fluorescent but not the LED.

[Narwhal72]

Did you actually read the articles?

http://biolum.eemb.ucsb.edu/organism/dragon.html

Why Red Light

The ability to produce red light, gives the Malacosteidae a huge advantage in the deep sea. Although the light doesn't travel very far, it lets them see their prey, without alerting the prey or any potentially curious predators. So these fish produce a red signal meant only for themselves, and a blue-green signal, perhaps used as a warning to others.

So you are missing the point. A red fish at depth does not look red to anything else because there is no red light it looks black.
http://oceanexplorer.noaa.gov/facts/red-color.html

Interestingly enough, the NOAA article says that red light penetrates to 100m which is far greater than I have ever heard. Most texts have it at 1-5 meters.

But you are right that most of our freshwater fish are from much shallower depths and probably have a much better sensitivity to red light. And certainly there are very few people with aquariums deeper than 5 meters so the point is pretty moot.

Andy

[dpm1]

How am I missing the point?

The ability to produce red light, gives the Malacosteidae a huge advantage in the deep sea. Although the light doesn't travel very far, it lets them see their prey, without alerting the prey or any potentially curious predators. So these fish produce a red signal meant only for themselves, and a blue-green signal, perhaps used as a warning to others.

So the predatory fish does emit red light which it can see but the prey cant thus instantly usurping the basic principle that no fish can see red light which was initially stated as:

Fish (or at least marine fish) are unable to see the color red because red wavelengths penetrate the water the least, so there is no reason for them to have the ability to see a color that basically doesn't exist in their world

The first part is species dependant as shown by the study (and others btw), and I have refered to the second below.
This light may not be travelling far but by detecting it they demonstrate a clear example of a fish doing precisely what many still believe they simply cannot do.

Being coloured red for a deep sea fish as a form of 'black' camouflage is very different to being a red fish that uses it as markings or signals which is what shallow water species are far more likely to do. It has nothing to do with seeing red and is a passive measure clearly different to the active seeing of the colour.

Another reason postulated as to why the majority of pelagic fish do not sense colours well and are predominantly sensitive only to short wavelengths is that these many colours simply do not exist in quantity outside of coastal regions - no shallow coral reefs, no plants, flowers, insects etc that carry much of the reds and yellows in the world. With nothing to look at why give over energy to detecting it?

The depth to which light of any wavelength can travel is determined by the optical density of the medium and sensitivity of the equipment. There no reason red can't reach 100m+, however if likely the levels at this depth are beyond most ability of most equipment. This is very different to what the human eye will deem acceptable. Although each individual eye cell is extremely sensitive the brain is more of an averaging machine particularly when the eye itself may still be seeing shorter wavelengths in far greater clarity .
....
I still believe red in a better colour for night lighting a freshwater aquarium, perhaps with dim light the second. Moonlight in shallow waters will not be filtered enough to make it blue and therefore I feel it makes it somewhat unnatural - whereas it suits marines well as the reef critters have evolved a degree of luminescence that works well and it shows up a different degree of detail, although I still have yet to see a reef fish that really looks anything other than a black hole under such lighting.

[Narwhal72]

There no reason red can't reach 100m+,

Beer's Law might have an issue with that.


Maybe I am misunderstanding the point you are trying to make. I think you are trying to say that fish can see red light. Which some fish definitely have the biological ability to see.

However, having the ability to see, and actually seeing something are two different things. At depth, if there is no red light then you cannot see red objects as red. Even if you have the ability to see red light at shallower depth.

But of course this is all pretty irrelevant to the OP's post. Light the tank whatever color you want. The fish really don't care.


Andy

[bekateen]

But of course this is all pretty irrelevant to the OP's post. Light the tank whatever color you want. The fish really don't care.

I know what you're saying, but this doesn't answer the question for those fish that can see red colors:

...if your fish do use red as a visual signaling color, then can we predict that red is automatically a poor color choice for a night light?

1. If red is used for aggressive displays, then would that tend to anger the fish? (which is bad)
2. If red is used to signal reproductive readiness, would that help get mates in the mood? (which could be good or confusing)

I suppose you could ask the same questions about fish that use blue colors to communicate in a tank lit with blue LEDs, although I can think of more fish that use red during aggressive interactions than I can blue.

Cheers, Eric

[dpm1]

There no reason red can't reach 100m+,

Beer's Law might have an issue with that.


Maybe I am misunderstanding the point you are trying to make. I think you are trying to say that fish can see red light. Which some fish definitely have the biological ability to see.

However, having the ability to see, and actually seeing something are two different things. At depth, if there is no red light then you cannot see red objects as red. Even if you have the ability to see red light at shallower depth.

But of course this is all pretty irrelevant to the OP's post. Light the tank whatever color you want. The fish really don't care.


Andy

Actually Beers law doesn't preclude it as there is a prerequisite that water cannot satisfy namely that the attenuating medium must be homogeneous in the interaction volume, and sea water being a particularly heavy chemical soup is notably nonhomogeneous in nature.
OK say the odds are so astronomically low that 100m really would be pushing it even for individual photons, however lake measurements in the US have easily exceed 5m to at least 8m+ which is far beyond the measures you stated earlier.

Clearly even the miniscule amount of red light that reaches beyond the surface layer won't be enough to illumate anything and I have stated that pelagic fish in general do not utilise red light, however I have also referenced a clear example of a fish that does, and through its own ability to produce it and not rely on external lighting. These fish not only produce the light but actively use it to hunt - the abilityy to see (have the physical capacity) and actually seeing (go use the information)

No where in previous posts have I categorically stated that 'fish can see red light' and yet its what is repeatedly being attributed to me. What I have said is that its been shown, both by observation and experiment of fish optic nerves that 'SOME fish can see red'. I have also stated clearly the difference between pelagic marine fish, shallow water marines, and freshwater types who are far more utilise red not only as a whole body colour but also as markings.
...
I have also already stated why I prefer to use red light in freshwater, and blue in salties.

[jodilynn]

None of my shy nocturnal species (my shyer synos, Midnight Cats, SA Bumblebee cats, my raphaels, even my more reclusive plecos) will come out with the blue light on. Tried to get them used to them by putting it on and trying to entice them with frozen food (which they love to pig out on) but to no avail.

Once I turn the lights completely off everyone comes out.

[bekateen]

I've been thinking about the nightlight idea some more. Specifically, I'd like to get a light (like a flashlight) that emits a color that fish don't see (or at least don't react to) so that I can shine it in my pleco caves to look for eggs/fry without disturbing the males or scaring them if they are in the middle of spawning. So I bought an LED flashlight with a red lens and used it to look in the caves of my clown plecos. The males were resting peacefully in the entrances to their caves; I turned on the light then pointed it in the caves. Each male reacted with panic and lunged deeper into his cave when the light shone on him. My verdict? Clown plecos can see this red light (sadly, I don't know the spectrum of this flashlight, other than its lens is red). Failure. Maybe I can find a blue flashlight which will work better.

[dpm1]

My Peckoltia also react to red light, albeit much less so than even dim white light. I have also ruled out that they are reacting simply to my own movements or others outside the tank.

I find they don't necessarily immediately run and hide, however, they definitely move away from the source of the light as though determining whether it's a threat or not.

Whole tank red lighting does not seem to illicit the same response as a point source light a small torch and the fish can be seen to emerge from their caves and move and feed quite readily (so its a pity I blew the transformer and am now back to only white/blue options)

[Marc van Arc]

Whole tank red lighting does not seem to illicit the same response as a point source light a small torch and the fish can be seen to emerge from their caves and move and feed quite readily (so its a pity I blew the transformer and am now back to only white/blue options)

And I would be very surprised if they wouldn't do exactly the same with blue light.
I respect your preference wrt using red light instead of blue, but you make it sound like things wouldn't work with blue light, which it does. I have seen it work over here for more than 10 years now.
And again, colour is personal. I use the blue because I like what I see. I don't use the red because I don't want my tank to look like something that belongs in a red light district.

Let me know if I have misinterpreted the above quote.

[dpm1]

Whole tank red lighting does not seem to illicit the same response as a point source light a small torch and the fish can be seen to emerge from their caves and move and feed quite readily (so its a pity I blew the transformer and am now back to only white/blue options)

And I would be very surprised if they wouldn't do exactly the same with blue light.
I respect your preference wrt using red light instead of blue, but you make it sound like things wouldn't work with blue light, which it does. I have seen it work over here for more than 10 years now.
And again, colour is personal. I use the blue because I like what I see. I don't use the red because I don't want my tank to look like something that belongs in a red light district.

Let me know if I have misinterpreted the above quote.

What I stated earlier was:

Actually red makes fish stand out under red light as a 'shape' although it is very poor for discerning details. As such it is a very good night light light in freshwater tanks as the nocturnal types can make much more use of it than the myriad of day swimmers.

Conversely marines exhibit very different effects and blue works much better...

Very dim white can also work in tanks to a lesser degree. Perhaps its not as effective at quickly drawing out true nocturnal types but has the advantage of allowing more detail to be seen.

So I have not said blue light wouldn't work, only that imo it makes freshwater appear rather sterile, although its better for detail.

I have in fact tried a blue light lifted from a saltie tank and the nocturnal fish took much longer to emerge from hiding (perhaps as a result of the fish not blending in as well from a distance as they do with red light?)

[Marc van Arc]

I take it we're (still?) talking about moonlight led lamps in a small (40 cms or thereabout) setting. For that is what I use.
In the times before leds I once bought a TL (58 W; 150 cms) in the blue colour that is specifically used for marine tanks. Well, the effect it had on my fishes was dramatic. They litterally tried to jump from the tank to escape from that light. The experiment lasted for about 3 minutes and then I decided to get rid of the lamp. So indeed, that colour blue didn't work at all.
Currently I use a much deeper blue which sits in the front middle of the tank and "lights" about 80(L) x 30(W) x 60(H)cms. The tank is 200 x 60 x 60 cms, so the fishes still have enough dark areas to swim in to the left, the right and in the back of the tank, where the moonlight doesn't shine.
Regardless of the colour, the leds are a huge improvement when compared to the old days when I used a night vision device from the army (quite illegal....) or had to put a piece of red cloth over my flashlight to be able to see my fishes in the dark.

[alleykat]

Hi everybody,

sorry for my absence. I have been ill, but am better now. Interesting to see the discussion, although I did not expect it Let's keep it civil and learn from the discussion. As far as the lighting is concerned, I see quite a lot of not so positive remarks; maybe I'll pass on putting one of these in my tanks.
I also find that my fish are quite easily spooked at night, so I would not want to aggravate that. Thanks everybody for contributing!

Alleykat

[Birger]

alleycat...I have Marineland lights on a show tank of mine and I really enjoy using the moon light feature..nobody freaks out and the synodontis are more active when they are on as opposed to the usual daytime white lights...and it looks kinda cool in the late evening.

So to answer your original question, for me I say I like them.

Birger