I only have 2 in my tank but it turns out they are a pair.
While feeding the fish tonight, 4 itty bitty serpae tetras popped out of the java moss. I have no idea how many in total there are but it was cool seeing these little ones. The largest of the 4 was swimming around grabbing flake food and the others which were smaller would dart in and out and grab a tiny flake.
Very cool!