I remember the Black Phantom Tetra on the tank when i bought them back in june.. i think your right about that one [Taelen]
and the other is a platy, i just thought because of it's odd color it was a particular kind. Blue Coral seems to match up very well with two pictures from Google image search. [fearlessfisch]
i have looked at the Serpae Tetra images as well. i do not think it is this type because it lacks the orange appearance the Google images had.
Black Phantom Tetra <Noname> is silver with little red belly-fins in front of a black-tipped dark grey fin from it's anal vent to it's tail fin.