The Onion Plant is a great and hardy plant for many aquariums because it's leaves are extremely tough, making it suitable for aquariums with larger fish!
Onion Plants are easy to care for and adapt well to most aquarium environments. They can grow to an impressive height of 60 inches (150 cm), with their leaves being about 0.8 inches (2 cm) across. Their leaves are extremely long and ribbonlike, and will start growing along the surface of the water once they reach it. Once they are well established you can cut the leaves back some to keep them from growing too long. Because of their height and long leaves they make great background plants for aquariums.
As long as the light is kept moderate to bright, Onion Plants will expend a moderate growth rate. As stated above, they adapt easily to most environments, so as long as the water is kept fertilized with nutrients, the water is cleaned on a regular basis, and the ph is kept around neutral, this plant should thrive. It is also relatively easy to propagate by simply planting the daughter bulbs that are produced.
For more Information on keeping a planted aquarium see:
About Planted Aquariums, Adding Aquatic Plants For a Healthy Aquarium