Fish Twitching

Interesting Reefkid. I only have 1 clown, but he does keep going down by the goby's cave and doing this. The goby is more dominate then him, is he just showing his submission over and over?
 
But I do not have another clown, would he submit to another breed of fish? He does it near my goby. And often when I move near the tank, I do not think he would submit to a human near the tank. lol
 
I have damsals that do the same, Different types of Damsal, but a larger fijian damsal swims around and when near others they twitch below him.

They also twitch when grazing around live rock sometimes. Think it's quite normal.
 
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