Red Light

[jonny_dw]

Is it true that fish cant see red lights?As some of you proberly know, piranha's dont really like aquarium lights and makes them quite skittish and timid. While I was in Brighton sea life centre in the summer I saw their red belly tank with red lighting and thought it looked quite good, so was considering it as a type of moonlighting.

If this is this case that they cant see red lighting then it will allow my fish to feel alot more relaxed even with a light on.

Cheers

 

[jonny_dw]

no one knows then?

 

[three-fingers]

I've heard it too, and I know people use red heat lamps with reptiles for the reason that they apparently can't see red. I'd ask this question in the science forum for a proper answer or tropical chat so more people can see it...not many people who potentially know will click on this topic here because they think it's a hardware question rather than a fish biology question . I'd quite like to know too.

I'm really not great at searching for this kinda stuff...but I can't find any studies that seem to regard it after a quick search. They probably exist, so better to ask in the science forum .

 

[Shrimper]

I don't know for certain but from my experience my old camera had a red light it used when focusing and it needed the flash and my new camera just has a white led. The fish never seemed bothered by the red light but don't like the flash or the white light.

I know its not a scentific test but its what I found

 

[The-Wolf]

I'm sure bignose won't mind me quoting him on this subject

The question of what light is absorbed the best really depends a lot on the fish's habitat and lifestyle.

"Morphology and spectral sensitivities of retinal and extraretinal
photoreceptors in freshwater teleosts" by C. Kusmic and P. Gualtieri in Micron volume 31, p. 183-200, 2000, has a chart that shows where in the light spectrum the different absorbancy maximas are. THe chart lists like 30 species, but are broken into 4 groups:

Group 1 are strictly diurnal species that live just below the water surface or live in shallow water. Some of the species listed are the guppies and swordtails. They have maximas in the violet part of the spectrum, right at 410-415 nm, and some in the blue part 460 nm. So, these fish should be very good at picking up blue light.

Group 2 are midwater swimmers, like barbs. Most of them don't have the violet peak, but the blue peak is present in almost every species this paper looked at.

Group 3 are nocturnal species, mostly predators. Group 4 are also nocturnal bottom dweelers, like cory catfish or red tailed black sharks. These do not have the violet or blue maximas at all, only the red ones.

However, it is obvious that like a lot of life, no one blanket statement can be said about all fish, depending upon their habitat and activities, the way they detect light varies.

taken from an old topic of mine (here)


HTH

 

[jonny_dw]

Ah so according to that, my fish is more likely to not see blue rather than red.

 

[The-Wolf]

hm, to me a piranah is a predator, thus you have it correct; they'd see red but not blue.
however piranah are also midwater swimmers so they may also see blue.

I guess you would have to find out either by trial and error (ie set up with red light, then blue light and see which makes them more comfortable)
or by finding a specific study or your species eyes (nigh on impossible I think)

personally both my tanks use blue light and both have top,mid and bottom dwellers

 

[jonny_dw]

Will do, thanks for the help.