YOu could go with pygmy sunfish (though they aren't real sunfish). You can pair them up with least killifish. Swamp darters mix well with these species too.
Pyramid - so here's another question - if shiners like to be in a school, will 2 be enough? Is it better to have only 2 in an understocked tank? Or squeeze in 1 more three inch Rainbow Shiner so that they can school together, even though it may crowd out the other fish??
