You'd want more than a couple. They are a very social fish and also need company to feel secure. If you had only two, you'd likely never see them.
They get to around the three/four inch mark (although being so long and thin, they have a small bioload), and would be happiest on a sand substrate, as they do like to dig.
They're very peaceful and wouldn't cause problems with your other fish.
Maybe after I get my cardinals, Molly's and bnp, if I'm not overstocked I might get some, I already have 5 blue angelfish, 5 espei rasboras and 5 albino corys
Is love to watch those videos but I'm away from home and I've no Internet here the 3GS on my phone isn't great but ill watch them when I'm home