China’s National Space Agency has released a video of part of a fish experiment being conducted at the Tiangong orbital station. Four small danio fish were delivered there last month. Their physical condition is good, but their behaviour is not.
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The main problem for fish in microgravity is that there is no concept of ‘up’. This was noticed back in 1973 on the space station ‘Skylab’, where two fish Fundulusa long looped around the aquarium, and eventually turned their backs to the source of light, taking it for the sun. The fish that hatched from eggs already at the station did the same.
The fish on Tiangong also exhibit behavioural anomalies. They can swim upside down, describe bizarre loops or move in circles. This surprises scientists, because these particular individuals are already familiar with microgravity, they have become leaders of strict selection – just like human astronauts.
