Red bugs (Tegastes acroporanus) are small flea-like beasts that can infest smooth-skinned acropora sp. Some reefers have gone out of their way to eliminate them from their reef tank, but that is not the purpose of this article. I've seen them in my tank on occasion, but never worried much about them. Maybe if they did more damage, I'd be more concerned. Still, whatever coral I saw them on, the coral wasn't as happy as it could be, because these guys are like little blood-suckers.