"Acro Bugs", aquarium pests that can infest your acropora colonies. These tiny little red bugs are almost invisible until close inspection. Once introduced into the aquarium, they can rapidly infest most all acropora species- inhibiting growth, affecting coloration and reducing polyp extension. They are most commonly introduced through coral trading from another aquarist without even knowing it.

More to come..

The link for the cure

http://www.reefs.org/phpBB2/viewtopic.php?p=439155#439155