These plants make excellent cover to get nervous fish more likely to come out and less likely to jump out.  These also give their fry a chance to hide and eat until they are big enough to surprise you. 

The fine, darker green plant is Riccia fluitans. I don't know the name of the lighter colored one. I don't want to call it duckweed because I'm not a fan of the little stuff that takes over. But I've seen frogbit and that is huge compared to this. So, I floated the penny on it for scale and to show you that it is a substantial plant when a few of them get together. You will receive a 3 inch diameter circle of each. (Penny not included, and definitely not recommended inside your tank.)