"David C. Stone" wrote in message
...
In article , NetMax
wrote:

"McEve" wrote in message
...
Assuming the animal, or fish, in question can see infrared light,
and
the pupil is able to dilate/retract - will the pupil respond to
exposure to infrared light?

I tried finding a more suitable newsgroup for this question, but
were
unable to find one. Maybe somebody here knows?


Can I assume this is a photographic question, so you mean very-near
infrared light (0.7 to 1.0um) as opposed to thermal or mid-infrared
(which doesn't penetrate glass ;~). This is a night vision question
on
your breeding Zebra plecs, isn't it? (how quickly we *see through*
your
question *oh bad pun*.

Water also absorbs very strongly across the IR band. I'm not sure
how much IR you would get in a fish tank, but I'm guessing not very
much and only select wavelengths at that.

My very limited understanding is that the longer the wavelength, the
lower the rate of attenuation. Water is blue because the shorter
higher-frequency blue is attenuated first and longer wavelength red
travels deeper. Similarly, lower musical notes travel further
underwater. Based on that logic, infrared should go further than visible
light with its longer wavelength, but longer is a relative term ;~),
water is a good attenuator.
--
www.NetMax.tk