Water Hyacinth consists of seven species types which are all native to South America. It is one of the fastest known growing plants. It can double it's population in 2 weeks. They can become a major problem when not properly controlled creating breeding grounds for mosquitoes and using up valuable natural resources.
i have tried to grow a couple of species of floating [I]Eichornia[/I]. i would not say that their aquarium culture is "easy". the plants that i had all declined over time. i think that it is difficult to provide the bright light that they require in a tank.
...And it DESERVES to be illegal. In India, where I come from, this stuff is a DISASTER. It's taken over ponds and streams. It chokes the waterways, leaving behind rotting swamps.... Kill it on sight!!
Well aside form it being an invasive species as mentioned above.. This is wonderful plant!!!!! I havent had any luck growing it in an aquarium, But I do have it floating as a sort of top level centerpiece in quite a few of my "fishbowls" I have lying around. They get alot of sunlight during the day and make a wonderful impression.. plus its also nice to have them bloom around the house throughout the year!!
They require a lot of light, even in a pond they will not grow and die off if it is too shaded to control the water temperature. You are better off using a shaded fountain or waterfall instead a stream to circulate the water so it cools better while still maintain sunlight in the main pond. Also, make it DEEP. The fish will just swim in the cooler lower water in the summer. Same for Water Lettuce, Lilies and most "pond" plants. I have both a pond and and some aquariums.