Last year I spent a month in Thailand. Everywhere I went there were these very large ceramic pots filled with water lilies or other water plants and tiny fish. They were so beautiful, and being a big fan of the water lily flower, I know I had to come home and make a container water garden of my own.
I would have liked to get a gorgeous ceramic pot, but they tend to be very expensive. So, a few months ago I was at my local home improvement store and came across a large plastic liner that would perfectly fit the half wine barrel I already had.
A friend of mine who has a pond directed me to Morning Sun Garden in San Gabriel. They had a good selection of pond plants and fish. It turns out that they only had large water lilies that would have been too crowded in my tub. I ended up getting Water Hyacinths, Fairy Moss, Anacharis, Anubius round leaf, Amazon Sword Plant, goldfish, and mosquito fish.
The Water Hyacinth and Fairy Moss float on top of the water. Water Hyacinth has a thick root mass that helps filter the water and the Fairy Moss acts as a sunshade. The fish like to nibble these two plants too. The other plants are submerged and provide habitat and oxygen for the fish. The Anacharis plant provides a lot of oxygen. I also added gravel to the bottom of the pond and a few granite boulders from my front yard to enhance the habitat.
Two other stores in the LA area that have a good selection of pond plants and animals are California Waterscapes and Sunland Water Gardens. It is a great joy to sit outside and watch the fish swim around in the water.