Learn about parrotfish and their role in reef communities, in this episode of Gross Science from NOVA. Parrotfish live in tropical waters near coral reefs. They eat algae that cling to the coral; pieces of coral pass through their digestive system and come out the other end as a fine, white sand. It is estimated that a single giant humphead parrotfish can poop out over 11,000 pounds of sand a year. Research shows that these fish help to keep reefs clean and healthy, and are an important part of reef communities. This resource is part of the NOVA: Gross Science Collection.