Comment by delichon

For long-term space habitation it will help to have a lot of shielding against radiation, and water is a leading option for that.

And it looks like fish do well in microgravity.

https://www.space.com/china-tiangong-space-station-zebrafish...

And they taste good. So maybe fish will beat birds to space habitats and astronauts will live in a hollow inside of large aquariums.