Lol I have seen my fish do that 3 times over 3 months or so but it is absolutley hilarious. The spines on his back stand up too. (yellowtail damsel)
Unfortunately have never caught the piture of it.
I guess it just so happened I clicked the camera at the right time! Salinity is 1.022. Just checked it! Thanks for looking out for me though! I had no clue what he was doing!