Baby tears is what we called it years ago but I can't remember the scientific name. the plant in the picture has been grown out of water and the leaves will change a little bit (but not a lot) when underwater.
Just an idea you say it doesn't fit. You can always take the tips off about an inch from the top and form them into a bush, then put them in the front of the tank. Baby tears is slow growing so will give you a different effect