Angel fish at my home

My parents just brought 13 angel fish to rear in my home aquarium.

Strange creatures are theses 13 angel fish.
All 13 of them just flocked together and move in a school.
Then suddenly, all of them would disperse and move in all direction, apparently in fear, whenever we make some noises. Days later, they started to spread up and ignore any noises.

Reflecting on them, human behaves in a like manner.

When one lands on a foreign land, one tends to look for similar race and origin to feel safety. That's why Chinatowns were formed over all the world for the Chinese.

Any slight changes would cause great fear. For example, one from an non-earthquake region in Malaysia would be overwhelm in fear when one first encounters an earthquake in Japan.

Beforehand, there's shaking, I better hide under the table.
After acclimating, the fear factor drops. earthquake?The shaking would stop soon while I continue to watch my TV.