In 1998, NASA sent oyster toadfish into space on Space Shuttle Columbia; over 16 days in orbit, researchers studied how their balance systems adapted to microgravity

A group of saltwater toadfish went aboard Columbia in April 1998. No one watching the launch would have guessed that fish were part of the cargo. Over the 16 days, changes inside their inner ears gave scientists a rare direct view of how a nervous system changes in microgravity. NASA's mission, STS-90 Neurolab, took off on April 17. It came back to Kennedy Space Center on May 3. It received less public attention than missions with a moon landing or a spacewalk, but inside the science world, it drew significant attention.

Why toadfish, of all creatures, made the cut