Congo Tetras and Buenos Aires Tetras are actually torpedo-shaped swift swiming fish similar to the Giant Danio, not at all like their cousins the black skirts or bleeding hearts. They can each get to be about 8"-12" when fully grown out.
Congo Tetras have a silvery body, with long fins that contain a purple irridecences.
Buenos Aires Tetras are silver in body, with short red or yellow fins.
I have kept these two speices of tetras in with oscars before without any difficulties what so ever.
~~Colesea