In 1973, NASA sent two fish into space to test their swimming ability in zero gravity; they initially swam in loops but later used light as cue to move normally after 21 days

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In 1973, NASA sent two mummichog fish and 50 eggs aboard Skylab 3 to study how weightlessness affected their sense of balance. The fish initially swam in strange sideways loops, but gradually adapted over 21 days, using light as a visual cue to maintain their orientation.