Eheim Auto Fish FeederEheim Auto Fish Feeder Eheim 3581090 Eheim has made the world first integrated automatic fish feeder ventilation system. The ventilation system and positioning of the container guarantees absolutely dry food. The ventilation fan blows a stream of air through the feed drum while it rotates. Therefore moisture is prevented from entering the food drum while the opening is in the downward position. Comes complete with batteries. Can also be manually