is it breathing rapidly? its perfectly normal for fish to freak out or lay on their sides but just keep a watchful eye. he should perk up soon

Flasher wrasses will often "play dead" (laying on their side on the bottom of the container) when stressed.

yes exactly the same, 5min finished , put it in the container with my aquarium water. is it safe not to let it go or not?

I think your good to put it back in the tank.

be careful to make sure that whatever was on it stays off it

I put it in plastic bag and watched it on light , I didnt see that thing, put in the tank, hopefully that thing died .

any ida what is that critter?

Thanks guys, it was very stressful for me specially for fish.

He is swimming normal in tank.