Emperor Blue Hook lost control swimming

[Censis]

Hi guys, please do have a look at my video and let me know what is wrong or anyone has encountered something like this before.

This is the second case of my blue hooks acting like this. I had one that died the exact same way as this guy a few weeks ago.

Tested water parameters, they are fine and all other fishes are acting and eating normally.

Have kept these hooks for over a year in my care, and not sure how long they've been kept with previous owner/(s). They are about 12 inches or bigger. Diet is kunning fish and pellets.

YouTube Video