Great thread.... if I were to do a 125 or something I would have to go with congos, they are incredible. Rummynose are always great schoolers, but then black neons and pristella tetras are very underrated as well in my opinion!
Axelrodia riesei.....Ruby Tetra. One of my favorite fish in general, actually. They're very interesting to observe in the aquarium and beautifully colored. They even get these really neat shades of fluorescent blue on their fins.