PENN-PLAX presents the 0.5 Gallon Aqua-Ponic Fish Tank and Planter. Each fish tank is made from ultra-clear plastic and replicates nature’s metabolic cycle by providing a healthy and symbiotic environment for fish and plants: as fish excrete waste in the tank the plant atop absorbs this waste as nourishment which in turn cleans the tank’s water. For those more interested in growing plants hydroponically our tanks can also be used strictly as a planter allowing you to add your own nutrients.