Good fish to school with neon tetras?

So I have a 20 gallon planted tank with six pacific blue eye, two corydoras and four neon tetras (introduced them yesterday). Ive only recently started putting fish in the tank. They seem to be going well and I need a couple more tetras to go in so they start schooling. What are good tetras to go with the neons? Also are there other fish that aren't tetras that will school with them?