Fainting fish?

[rbeth]

I am new to posting so forgive me if I do something wrong.
Is there an illness that cause fish to act like their scared and then sink to the bottom of the tank and look dead, then after a few seconds they get up and swim away like nothing was wrong.

ammonia 0
nitrites 0
nitrates 10
ph 7.8

 

[Terry]

There are several fish that do this, a good example is the neon tetra. It is basically a defence mechanism. Neon tetra will shock themselves if they feel threatened and after a couple of minutes they look as though nothing has happened.