Garden designer Mayita Dinos explains how to create an entire ecosystem in a pot. Everything needed to support aquatic life can be contained in a large pot. Incorporate floating plants to supply oxygen, plants such as the submersible canna for interest and algae control, snails to keep everything tidy and fish to control mosquitoes. Fill the container with water, and let it stand for a day or two to allow chlorine to dissipate. Chlorine can harm fish and aquatic plants.
Planting begins with a hardy water lily.
Leave the plant in its original pot, and place it directly on the bottom of the water-filled container. If the plant is too low in the water, prop it up with a brick until the leaves just reach the surface of the water. As the plant grows, you can remove the brick. The plants will spread out and look natural after they've settled in for a week or two. The water may be murky until the mud settles.