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The red and black fish in your photo is a red wag platy (Xiphophorus variatus). I believe the two other fish, black ones, are lyrtail black mollies. The Platy has more of an oval shape to its' body. Mollies have a more pointy head that slopes into a rounder bellied body. Check out this picture of a molly and see if that is what you have. http://i1282.photobucket.com/albums/a530/Cyndie47/Black_Molly_zps47a9a84d.jpg