'Tis the season for pond plants! Water Lettuce in particular can be very attractive in aquaria. It floats, so you may need to drop your water level an inch or two, but having leaves out of water allows it both to collect more light, and to use more light without having to add CO2. It will rapidly multiply and can shade the surface as much as you allow. And the fuzzy roots hanging down are kind of attractive, and definitely a very good thing to have if any fish are breeding.
