That looks a lot like a Peacock Mantis,though the color is off.
Sale that dude.He sould be good for 30 or 40 bucks.:D
But I could have told you an easier way to catch him than taking all the rock out.
The next mantis you get,place your net in the tank with a silver side in it.Do that daily until the mantis get comfortable eating out of the net.Then tie a string or fishing line to the handle of the net once the shrimp gets comfortable,then its as simple as sitting back and setting the hook.:D