It"s suitable for flakes, granules, or other dry, loose types of fish food. * the plastic food drum of this automatic feeder is designed with moisture-proof features. * The product will automatically release a programmed amount of dry fish pellets into your fish tank. * The Automatic Fish Feeder can be easily clipped to any type of water tank or containers. * owered by 2 AAA batteries (not included), the Automatic Fish Feed can last for days.