Spath, often sold as "Brazil Sword" is not aquatic. It does, however do very well as a water rooted plant. I have used them, very successfuly, as filter plants. If they were grown in soil you must cut off all the soil roots and put the stem in water. The stem will then grow water roots (a different type of root) and live happily with the roots sumberged indefinitely. I don't know how long they can survive with every leaf completely underwater from my own experience, thogh people say several months to half a yeear. They will definitely try to break the surface before they die.