An air pump helps keep your aquarium water oxygen-rich by driving bubbles and creating surface agitation, which improves gas exchange and ensures your fish can breathe easily - especially important in heavily stocked tanks. They can be attached to foam filters for an inexpensive filtration option or connected to air stones and bubble walls that both oxygenate the water and add visual interest. Air pumps are also handy for powering small decorations, and you may find it easier to run a few smaller units spaced evenly around your aquarium if you need extra circulation. For best results, pair your pump with an air stone or diffuser for finer bubbles and quieter operation, since proper oxygenation is vital to a healthy, thriving tank.