Eight medaka fish hatched in space during 1994 Columbia mission

Japanese astronaut Chiaki Mukai carried four medaka fish aboard the Space Shuttle Columbia in July 1994 to study reproduction in microgravity. The fish successfully laid eggs during the mission, with eight out of 43 identified eggs hatching while still in space. The experiment provided valuable insight into whether aquatic vertebrates could reproduce in a weightless environment. Upon returning to Earth, the adult fish gradually readapted to normal gravity, while the young fish born in space continued to develop healthily.