Water sprite (or Ceratopteris thalictroides if you want to get scientific) is a highly versitle plant. You can keep it floating at the top of your tank. Just throw it in. When floated, water sprite will quickly multiply once established. I grew it like this in my 125 under high light and CO2 and it grew like crazy. I had runners all over the place...
What is cool about Water Sprite when floated is that is produces extensive, sweet looking roots down into the tank. It grows wide leaves that attempt to cover the waters surface. My angels loved this and your fish will like it as well. This is also beneficial for newly hatched fry as well as they can hide in the big roots. Water Sprite can also be rooted down just like a normal plant. It doesn't have the hardiest roots so you'll want to get it down in there pretty good. When grown under water it will have skinnier branchy leaves that look entirely different when grown above the water.
2-10 UPDATE: I have about 10-12 inch watersprite in right now! It's a fun plant to always have some around--get some.