Help stocking a 20 gallon long

I've recently purchased a 20 gallon long as an upgrade from my 10 gallon. At the moment I have my 4 khulis, a female betta, and a nerite snail in the tank, I'm going to be getting a few (2-3) more khulis but what other fish would you recommend I add? My substrate is sand and it's a moderately planted tank, I have a strong filter and do weekly water changes :)