fish strange behaviour. (video attached)

[fishhelp]

i just saw one of my fish swimming weirdly. i tried to attach the video here. but due to technical limitation i couldn't.
so i uploaded it to YouTube. please help me identify the problem.
Youtube link

 

[Naughts]

Has it been trapped somewhere? It appears to have severe neurological damage to the spine and brain. Sorry, it would be kinder to euthanise him.

 

[Slaphppy7]

Agree with the above, that fish is severely deformed, and suffering.