This is such a lousy title for what I think is a good idea. I just blanked on that part....

This idea builds on [8th of 7]’s “Hamster Wall-of-Death Enclosure” and [Maxwell Buchanan]’s contributions to it, “Wall-of-Death Aquarium,” which featured fish enclosed in a vertical cylinder. Neither of these has much to do with death, as it turns out, but it did give me inspiration for this idea.

I have been informed by respected biologists that fish orient themselves while underwater primarily to the direction of incoming light. There are exceptions, but most fish swim with their backs towards sunlight (up).

“Correlation does not imply causation,” as the maxim goes. In other words, just because fish swim ‘upright’, it does not automatically prove that they do so in response to a light source.

Thus, scientific experiments were undertaken upon fish in tanks in which the light source was moved to the side, to the bottom, etc. The lab fish altered their notion of ‘upright’ to sideways and even upside-down, in response.

SO, I propose a cylinder-shaped aquarium, say two feet in diameter, and two feet long (or high, as the aquarium rests on one end, that is, as a vertical column. The aquarium- column will have a smaller, hollow cylinder installed in the length of its longitudinal axis. A tube within a tube, if you will.

The inside surface of the outside glass--where the fish swim--is a one-way mirror, transparent from the outside, for observation and enjoyment.

A light source is installed in the center hollow tube. The fish will perceive the inside wall of the outside tube as the ‘bottom’ of the aquarium, the lighted inside tube as ‘up’ and therefore, swim sideways, bellies toward the viewer, backs towards the light, providing amusement, education, and happily confused fish.

It seems likely to me that fish respond to gravity as well as light. With this in mind, the entire tank assembly could be rotated on its axis, providing centripetal force, which would help counter the actual force of gravity, and maybe confuse the fish further.
-- Boomershine, Oct 08 2010

How to confuse a fish. http://www.med.nago...834/NJ580301071.pdf
See section "Disorientaton of fish exposed to microgravity" [mouseposture, Oct 09 2010]

The light business.....I wonder. Does anyone happen to have an aquarium, some fish, a dark room and a torch?
-- MaxwellBuchanan, Oct 08 2010


I was wondering this myself..and, as an after-thought, why this wouldn't work on a regular rectangular aquarium with all sides, save one on the side, blacked out. Seems simple enough to try...and intuitively unlikely to work.

Still, science says it works. I imagine it might take awhile for the fish to get used to this arrangement and not notice their feces dropping sideways, or bubbles passing them horizontally.
-- Boomershine, Oct 08 2010


This needs to be built.
That is all.
-- 2 fries shy of a happy meal, Oct 09 2010


Brilliant, [Boomer]! It would be fun to see them in a zero-gravity environment, too. Bun! [+]
-- Grogster, Oct 09 2010


Inside the San Francisco Aquarium is a large cylindrical tank. From distant memory, it's on the top floor and the circular space in the middle must be entered from below, meaning that once inside you have a 360 degree view of the surrounding water.

This water contains rapidly swimming barracuda fish, who orbit the tank, moving against a strong current. I recall a the tank being bathed in cool blue light, in an otherwise darkened room. For some time I was alone with these amazing fish.

I had a friend who worked there as an engineer, so he was able to take me in when the place was closed to the general public.
-- xenzag, Oct 09 2010


This walk-in version sounds delightful and could be implemented.

The more I consider this concept, the more I doubt the science of my own idea. It's so hard to imagine fish orienting themselves to the light when they have swim bladders that orient to gravity. I wish I had more data on those experiments...
-- Boomershine, Oct 09 2010


"When a fish is illuminated from the side, it tilts its body vertically 20-30 degres so as to turn its back toward the light source. This tilt response is called the 'dorsal light reaction (DLR).'" (Note that the tilt is less than 90° i.e. the gain of the reflex is less than 1.0)

However, "fish can maintain the upright posture in darkness," so there must be other sensory sources of information about the vertical as well. Not only that but otolith-removed fish can accomplish this feat. The <link>ed article speculates that "the swim bladder may be a candidate graviceptor organ." Just as you said.

One of the best things about the HB is how it sends one off to research topics one would otherwise never have thought of. Who knew, for example, that fish-otoliths are the subject of a huge literature having nothing to do with their utility to the fish?
-- mouseposture, Oct 09 2010


//One of the best things about the HB is how it sends one off to research topics...//

Amen to that [mp]! Thanks for the link. I searched too, but didn't think to include "confuse" in it, even though I used the word in my description.

Btw, I've seen cod otoliths made into jewelry in Alaska.
-- Boomershine, Oct 09 2010


Cylindrical tanks with a hollow inner cylinder exist, I've seen one and it was cool. I think they're for Angel fish or Jellyfish. The hollow tube in the middle is for water to overflow into. You then filter it and pump it back in. It would be easy to put a strip light in the tube.

If the outer wall was a one-way mirror, it would reflect the inner light so it would be like 2 light sources, so not ideal.
-- marklar, Oct 11 2010


//If the outer wall was a one-way mirror, it would reflect the inner light so it would be like 2 light sources, so not ideal.//

I actually started on that problem in my original description, but scrapped it, hoping no one would think of it, fool that I am. Still, the reflecting surface would not be as bright as the actual light source.

It would be really cool if fish were perfectly light- reponsive. Then you could flash the light source on and off from different directions and the fish would all flip together in response.
-- Boomershine, Oct 11 2010



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