Interesting Facts About the Fish that Poops Sand – Parrotfish

Parrotfish about to poop sand

Fish pooping waste isn’t surprising. But have you ever heard about the fish that poop sand?

Parrotfish is the only fish species that poops sand, and it’s a fascinating fact.

So let’s learn more about this weird fact. But first, let’s take a look at some fascinating facts about Parrotfish.

Interesting Facts About Parrotfish

Parrotfish belong to the Scaridae family or a subfamily Scarinae of the wrasses.

Currently, there are around 90 identified species of parrotfish.

These fish are found in shallow subtropical and tropical oceans throughout the world.

They primarily inhabit the coral reefs, seagrass beds, and rocky coasts.

Parrotfish sizes vary as per the species, with most reaching 12 to 20 inches in length.

However, a few species grow bigger and reach around 3 feet 3 inches in length.

The green humphead parrotfish is the largest species reaching 4 feet 3 inches in length.

On the contrary, bluelip parrotfish is the smallest species, reaching a maximum size of 5.1 inches.

Parrotfish are primarily herbivorous grazers and eat algae off coral reefs almost all day.

They also play a crucial role in maintaining healthy reef ecosystems by consuming algae that may smother coral.

These fish feed mainly during the day and sleep at night.

They secrete mucus from glands near their gill to make cocoons for sleeping.

The cocoon keeps them protected from parasites while they sleep.

Another distinct feature of parrotfish is their reproduction technique, which is accompanied by a series of gender and color changes.

Most species of parrotfish are sequential hermaphrodites, meaning they start as females (known as the initial phase) and then change to males (terminal phase).

However, the stoplight parrotfish directly develop as males, meaning they don’t start as females.

While other species, such as Mediterranean parrotfish, are secondary gonochorists, meaning they don’t change gender and remain females throughout their life.

The marbled parrotfish is the only species of parrotfish that is known for not changing gender.

For most parrotfish species, their color in the initial phase is dull red, grey, or brown.

In contrast, their color in the terminal phase is a bright color such as blue or green with bright pink, yellow, or orange patches.

How Parrotfish Poop Sand?

Most parrotfish species are herbivores. In the wild, they mainly feed on epilithic algae and fallen corals.

Parrotfish are famous for their unusual dentition.

These fish have unique tooth structure that enables them to eat coral without breaking them.

They have roughly 1000 teeth that are lined up in 15 rows.

These teeth are cemented together to form the beak structure, which parrotfish use for biting the coral.

Parrotfish primarily chew coral all day long.

Along with the hard calcium carbonate coral skeleton, they also consume the soft-bodied organisms (called polyps) that cover the skeleton.

In addition, these fish also eat the algae (called zooxanthellae) and the bacteria living inside the coral skeleton.

Since parrotfish don’t have a stomach, they simply gnaw off the algae and calcium carbonate.

They then grind it with teeth located at the back of their throat, known as pharyngeal jaws.

Corals get crushed between the bony plates, and the coral fragments get grounded in the intestines of these fish.

Their digestive system absorbs the nutritious algae and excretes the calcium carbonate milled into fine sediment that comes out as sand.

How Do Parrotfish Help the Reefs’ Ecosystem?

Parrotfish swimming over a reef

Coral reefs face many threats such as pollution, overfishing, climate change, etc.

However, parrotfish play an increasingly important role in maintaining healthy reef ecosystems.

These fish spend around 90% of their day cleaning the algae reef.

They love to chew on fallen coral, vital in revitalizing the reef ecosystem by removing the excess algae.

Parrotfish consume and remove the macroalgae, which otherwise may cover the reef, thus causing it to become unhealthy and hinder its growth.

Removing algae from the reefs allows them to continue their natural processes.

This cleaning is crucial for the survival of the reefs’ ecosystem.

By eating algae, parrotfish prevent algae blooms, which can cause coral bleaching and result in the corals perishing.

Algae is a major threat to corals as they steal nutrients from the water column.

Algae can grow so fast that they can block light penetration, making it difficult for corals to photosynthesize.

Algae also compete with the coral polyps for space. If there are too many algae, the polyps won’t grow well.

When parrotfish eat algae, the coral is able to grow and become more resilient to pollution and warming,

Parrotfish also help to keep the reef free from debris.

This helps to maintain the reef’s health by preventing the buildup of harmful substances.

The digestive system of parrotfish breaks down the coral bits into white sand that makes up the reef.

Also known as “bio-erosion,” this process helps to control the algae population and creates new surfaces for baby corallines to attach to and grow on.

Finally, it’s found that coral reefs aren’t as reproductive and can’t sustain as much diverse life in areas where overfishing has wiped out the parrotfish population.

How Much Sand Does Parrotfish Poop?

Parrotfish poop a considerable amount of sand. The contribution of parrotfish poop varies from place to place.

The king of all parrotfish, the giant humphead parrotfish of Mexico and the Caribbean, can poop almost 5 tons of sand a year.

Scientists estimate that parrotfish have excreted up to 70% of the sand on Hawaii and Caribbean beaches, and approximately 85% of the sand on Vakkaru Island of the Maldives is parrotfish poop.

Scientists have also estimated that a single chlorurus gibbus parrotfish, also known as the heavybeak parrotfish, can poop more than 2000 pounds of sand each year.

Large parrotfish are considered as sand factories because of the amount of sand they excrete.

They’re also called “uhu” in Hawaiian, meaning “loose bowels.”