I prefer to use the common name, then the scientific name in parenthesis such as Coral Beauty Angelfish (Centropyge Bispinosus) that way its easier for most people. In conversation I usually say the common name, because I almost always either mispronounce or just don't know how to say the scientific name. For example, even to this day I still occasionally pronounce Centropyge as "Cen-Tro-Page" when it is actually "Cent-Roe-Pie-Gay."
I still think I mispronounce half of the scientific names though; luckily I can recognize the scientific name that goes with the fish though.