Not positive but I think thats "Willow Leaf Hygrophila" - Hygrophilia corymbosa 'angustifolia', which is a stem plant and as such will take most of it's nutrients from the water column. That's not to say it won't take any through the roots - but it's roots are mostly to anchor the plant in the substrate. I's use a liquid fert before I'd use root tabs with this particular plant