I use a small water pump enclosed in a tupperware container with small holes drilled in to allow water through. The container is covered with natural pea gravel and acts as an under gravel/biological filter as the water is drawn through the gravel particles are captured in the gravel. Water and gravel are siphoned once a week with a 50% water change. I keep them in a 20 gallon bow front half filled with water and planted on the back--vivarium. I feed them 1 to 2 times a week frozen blood worms and sometimes fruit flies. They've survived for a couple of years.