Swimming in a fishbowl 380 kilometers above Earth, they flipped, spun, and struggled to find their bearings — until they adapted. For 43 days in 2024, four zebrafish orbited China’s Tiangong space ...

This story appears in the September 2017 issue of National Geographic magazine. For a creature that’s less than one and a half inches long, the zebrafish (Danio rerio) looms large in biomedical ...