Id Please!

I was looking at my tank with a flashlight tonight and saw a dark colored beetle like creature on my candy cane coral. It was about a 1/4 inch from end to end, looked like a bedbug and crawled very fast. Tried to dodge my flashlight for a bit then disappeared into the rockwork. Just added a hammer coral and the candy cane, but they were both dipped with Coral Rx. Can anyone steer me in the right direction? I've been looking at pics, but no luck so far.

 

Type of zooplanktons? Check out link:

Hitch Hiking Copepods, Isopods and Amphipods

If not there google Black Bugs, but I do not think that is it.

 

Looking at that guild, might be some kind of mite.