Halfbakery Idea Implementaion: Roaming Fish

I don’t know if anyone here is familiar with halfbakery, but it’s a pretty neat site where people post concepts they wish were a reality. Anyway, this one idea caught my fancy:

Modelled on those transparent balls you can put hamsters in to let them run safely around your home, this is basically the same but built for your fish.

At some point on the sphere is a watertight, screw-on panel which can be removed in order to get the fish inside. To get the fish into the sphere, you simply push it into the fish’s normal aquarium, and the fish will be sucked in along with the the water. Then remove ball from aquarium, dry off with towel, and set the ball on the floor.

Now, I’m pretty sure this next bit won’t work, but it almost seems to make a strange kind of sense. As the fish moves toward the edge of the ball, the weight distribution in the ball shifts, and the ball itself shifts with it. Thus your little fishy can swim through your house just as effectively as if you’d flooded the whole place knee-deep in water.

As I said, I’m fairly certain that things won’t be that simple, given the fish’s swim bladder and its bouyancy and probably lots of other things that I don’t know anything about either. I did try to come up with another mechanism for making the ball move with the fish, but the best I could come up with was the equally improbable mechanism of having the water filled-ball surrounded by another slightly larger ball which contains a couple of weighted ball bearings. Attach a magnet to the fish (another potential stumbling block, I’ll agree), and as the fish influences the ball-bearings, the ball moves.

Still, even if the fish can’t get the Bowl moving itself, the whole setup would make an excellent cat toy.

Now, his grasp of the physics involved is, shall we say, a bit off, but the concept is a neat one. So aspiring and formerly aspiring engineers, how would you implement this? I think you’d need some little turbines so the fish is never really able to move out of the center of the tank. I would make the fish tank cubic and have webcams on the top and side and write software to interpolate position. From there you could move the tanks platform around based on fish position. I think you could pull this off with the KOP, some little water turbine things, and a cheap webcam or two. Would the fish dig it? :rolleyes:

This will not work and here’s why…

If you put a hamster into a globe he’s surrounded by air. The air has zero effect on the physics of the globe rolling because the air is both inside and outside of the globe. The only mass inside the globe is the hamster. The hamster is able to make the ball move by applying force against the wall of the globe. Since there is no other mass in the globe there’s nothing from stoping it from moving. (of course this wouldn’t work for any other shaped object, say a square) Basicly, the hamster is changing the center of gravity of the sphere causing it to move in an attempt to bring the center of gravity to the middle of the sphere again.

If you filled a globe with water and inserted a fish into it the fish would not be able to significantly change the center of gravity. The fish would weigh so little compared to the weight of the water that it just wouldn’t work.

EDIT: Sorry, after re-reading I realized you already knew it was impossible.

Not to mention if the ball was completely watertight and sealed, then that poor little fishy would die. I’ll admit, it would look cool though. Maybe you’ll see this in some animated weird show or sci-fi movie some time in the future.

It would be as odd, as say… Flying toasters? :rolleyes:

This kind of reminds me about the patent I once researched about toilet tanks that were transparent on the front and split in half so the front half became a fish tank… I think if I ever went to use one I would freak out thinking the poor fish would get flushed if I depressed the handle! :eek:

I had a fish once. It had nice big tank with lots of plastic plants and little castle and all sorts of things I thought would fascinate a little fish brain.

The dopey thing either floated in the middle of the tank or swam around in circles. Then the cat got him. I wasn’t to broken up about it. Having just learned about Darwin in school, I figured that the cat had proven him self a superior pet.

From what I’ve seen of fish in other tanks, I don’t think mine was being very original. All fish seem to either do nothing or wander aimlessly till they see food. I guess it has something to do with only having enough brain power to handle instinct. I know some people like fish, but they really are quite dumb.

So my question is, if the fish can’t find it’s way around a tank, how is it going to handle my house?

-Andy A.

That is possibly the coolest thing I have ever heard. ever.

edit: OMG… :eek:

Only 1,100.00 each.



Oh… Apparently the fish are **not **included with the bowl… :rolleyes: Oh well.

It’s a good idea just as long as that isn’t toilet water. But then again, those fish would probably die with the coming stop to the lavatory.

My goldfishes are somewhat stupid.
All they want to do is eat, eat, eat, and then do the other business caused by over eating.

If I put them in one of these roaming balls, all they want to do is search around for food and get themselves into trouble with the neighbor’s cat.

If it could work (go find some lightweight water… :rolleyes: ) the fish could safely play with the cat -or- start chasing the cat and have fun with its :cough: low oxygen deadly :cough: fishbowl. But the goldfish probably wouldn’t mind. Now all you need is a solar-powered revolving light that stays bouyent in the middle of the globe, just to add that special pinch of robotics to the recipe.


It’s not really an issue of lightweight water. In order for the fish to not float to the top or sink to the bottom, it adjusts its swim bladder so that is exactly the same density as the water around it. If the fish were heavier than the water, it would sink.

Why do I want my fish loose in the house?

Instead- how about making a big hamster ball that would hold a human inside that would roll along the bottom of a lake so you can cross over while observing the fishes in THEIR home. I guess if you got tired you could make it less dense than the water and float to the surface.

WC :cool:

The thought behind the lightweight water is that the fish would be able to make more of a difference in weight if the water didn’t weight as much.

As for the human bubble- that would be kinda fun, provided you have enough air and the bubble never broke.


C’mmon folks, Now how about some ideas about how this little ball COULD be made to work,
It was on the website as a fun idea that doesn’t work without some helpright?..

Example, how about a metal sphere that sits at the bottom of the ball.
Use a processor and sensor to sense the position of the fish in the ball, and move the metal sphere (by means TBD) to always be under the fish.
The sphere, being much denser than the water/fish will change the center of mass location and cause the ball to roll in that direction.
How, maybe use magetic fields or magic to move the metal sphere.
You’re doing work to accelerate/move the ball system around the floor, so you’ll need a power source - battery, corn dog or something. Maybe the fish can be trained to turn a little generator wheel.

Hmmm… I seem to have recalled a little invention that does that. Probably a submarine, lol. But iit would be cool to have a ball where a human can walk underwater. Unfortinatley, the pressure rises as you sink to the bottom and thus, this will break your ball easily. Also you need SOME sort of oxygen tank. Something that can convery carbon-dioxide to oxygen, hmmmmm? (if that was ever possible, lol). Plus, you need to make the ball have a density of 0 (that means the oxygen inside it too and the human).

Example, how about a metal sphere that sits at the bottom of the ball.

Hmmm… we could also try a design like a robo-maid but it would be designed so the fish can see where he’s going, and it can detect the position of the fish. I would say the sensor system would be on the top. Have it like an infered system. Once someone figures out how to make a fish survive in the ball, all it needs to do is move and the infered will tell where the center is, where the fish is, and move according to where the fish is. I’m sure it can work. :slight_smile: