Watch fish in this inverted aquarium, aka a fish condo

Originally published at:


I wonder if the water feels funny; like the fish have the same sensation we do in a glass-bottomed boat?


“Fish condo” is my word of the day. It made my day.



Fish in tanks are never scared of what I expect them to be scared of. I have a somewhat tall tank in my entryway with angelfish – when anyone walks near the tank they are interested, curious, not at all upset. But any movement above the height of the waterline is terrifying to them. I assume they’re wired for an environment full of herons but relatively free from giant aquatic predators. Fish breeders generally keep their breeding tanks up high because a lot of fish will never spawn in a tank on the floor.

Given that, I’d expect the fish to feel more secure in the condo, since it gives them a height advantage.


I wonder whether the oxygen level in the condo gets depleted because the water isn’t in contact with fresh air.


Webteam! Quickly! We must leverage the social media potential of the early fish condo adopters!


So was the builder of said condo, pumping water into it? or vacuuming the air out? I’m a little curious about all the physics involved. How much force is being put against the glass? How much stress? I’ve been thinking about adding a water feature to my ard and would love to do something like this.

Three words: tiny fish houses.


Any fishtank that can hold water right side up can rather obviously hold water upside-down. As to how to fill, personally I’d fill the condo-tank to the brim, submerse it in the main tank, then invert it and lift to the desired height. Keep in mind that no matter how you do it, you have to raise a tank-full of water. Same problem if you use a pump to exhaust the air: you’re still working against gravity/air pressure.

1 Like

Still, the pressure on the glass would be reversed so depending on the tank design it’s possible that one created to withstand force pushing outward might not withstand the force of being pulled inward.

Imagine a collapsable water bowl like this:

When filled with water the pressure actually helps it retain its shape. But you wouldn’t be able to turn it upside down in a pond and pull it up, because the sides would buckle inward when you pulled upward from the bottom.


Indeed, freedivers report fish being completely unconcerned about them in much the same fashion. Guess unlike scuba divers, there’s no disturbances in the water, and a person doesn’t obviously look or move like a predator.

1 Like

that was my question, too.

i suspect the primary reason water cycles is due to heat, and it seems like the glass tower would setup its own dynamics which would interact with the water below pretty freely. the fish themselves might even help facilitate that as they swim around.

( just my guess. )

1 Like

Ain’t that America, home of the free
Tiny fish houses for you and me


This topic was automatically closed after 5 days. New replies are no longer allowed.