Yes, you read that title correctly. I saw the claim in "Colonies in Space", hosted on the NSS site.
In a weightless space farm, it may be possible to raise fish without water. On Earth, when a fish is taken from water, gravity makes its gills collapse so that it cannot get oxygen. In weightless space these same fish might easily "swim" through an atmosphere of 100 percent humidity, keeping comfortably moist: hydroponic fish, if you will.
This sounds completely bonkers. Could astronauts aboard the ISS open up the fish tank and let them "swim" (or flail randomly) about the station?
Are there not problems with Oxygen availability? Even if the limit in air on Earth is collapse of the gills due to gravity, can a fish really survive getting air instead of water? Are there any credible references, or a sound scientific case that this is possible? Why hasn't it been attempted in experiments? Do gills even work that way?