You are correct ua...it prefers damp soil, but unfortunately is not aquatic. You should remove it before it dies and fouls the water. They do look fantastic as houseplants, and some varieties fold their leaves at night. Cool plant, but not for aquariums.
I would take it back and complain for selling house plants as aquatic plants. Sorry they got you!! its crap they set people up for failure from the start for no reason. Its the dumbest marketing I have ever seen make people hate real plants so they buy fake ones.