I found a really neat ceramic bowl on clearance last year. The inside had a really neat glaze so I didn't want to plant anything in it, I wanted to be able to see the colors. So I decided that it should be used for a container water garden.
I purchased 2 water lettuce and a water hyacinth to start with. I then added some frog bit, a tiny floating plant that multiplies and eventually will cover more of the water surface. I also added a beautiful hand-blown glass float.
My water garden required very little maintenance, mostly it needed water added every once in awhile. I found that the plants did best with morning sun and then partial shade, particularly the water lettuce, as the afternoon sun burned the leaves. The only issue I ran into was mosquito larvae, which was easily solved by purchasing floating mosquito donuts and cutting off a small piece to float in the bowl.