That does not (to me) look like Tegastes. In all likelihood, it is just a non-parasitic variety of copepod.
If you are real serious about acropora, you might be well served to start the hunt now to get your hands on Interceptor (milbemycin oxime) just in case we are wrong, or you encounter some later. If you have a dog, it is pretty easy. If you don't, find a friend that does. It is exceedingly difficult to get a prescrip for off-label use like ours. It is not very perishable and good to have on hand.