How Much Sand Do Parrotfish Poop?

several brightly colored fish in an aquarium

You may have overheard in our feeding presentation that parrotfish poop sand, but have you ever wondered how much sand they produce?  It turns out, a lot!  First, in case you haven’t heard our talk yet, parrotfish eat algae off rock surfaces.  When they do this, they ingest little bits of rock with each bite.  That rock goes through their body and comes out as sand!  Some researchers have investigated this and found that in the Caribbean the small stripped parrotfish (Scarus croicensis) can produce six pounds of sand a year!  Pretty remarkable considering the stripped parrotfish is usually only about six inches long.

The truly amazing part is when we consider larger parrotfish.  As parrotfish increase in size, they produce more sand, but it is not a linear increase, or one to one ratio.  The amount of the sand they produce increased exponentially, in other words, an increase of one inch of fish increases the sand production by 10 to 100 times!  For example, our 12-inch blue parrotfish (Scarus coeruleus) in the Coral Reef aquarium can produce not 12 pounds of sand, but 100 pounds a year!  And blue parrotfish are regularly observed up to 24-inches or more.  For an example of how much sand that they may produce at that larger size, we can look to the Pacific Ocean and the steephead parrotfish (Chlorurus stronglyocephalus).  Two researchers working in the Maldives found that the 28-inch steephead parrotfish can produce a whopping 900 pounds of sand per year!!! When you consider these larger amounts, it is easy to understand how scientists estimate that more than 80% of the sand around tropical coral reefs is parrotfish poop!  Of course, we are not talking about our Florida beaches, most of our sand comes from the erosion of land and is transported by rivers to the coast.

I hope you enjoyed learning a little more about our parrotfish and why they are so important to tropical coral reefs.  You can do your part to help these fish out by following the local regulations when fishing, as all species of parrotfish in Florida are protected at larger sizes because they are so vitally important.  And make sure to come by and check out our many species of parrotfish in each of our four large aquariums!


close-up of a parrotfish head and mouth

From: Hammock Happenings, January - February 2020

By: Bryan Danson, Aquarist

Category Tag(s): Nature Blog