What kind of fish is this?

OK, I bought some small fish, about the shape and size of minnows for my aquarium. They were cheap. So I could afford them. They are about 1-1/2" long, freshwater, schooling fish, move around a lot! Grey/clear bodies toward the tail. Grey on top, white on bottom. A black line along the side. A small black line down behind the head, in front of the side fins. I know they are not any thing special, but I like them and they are friendly.