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The Explorer's Guide contains a treasure trove of aquatic science resources developed for use in K-12 classrooms. Back to Explorer's Guide.

Bicolor Parrotfish Cetoscarus bicolor
Bicolor parrotfish sleep in slimy bubbles. Before going to sleep in a reef hole, this parrotfish spins a cocoon around its body. The slimy bubble hides the fish’s scent. This protects the parrotfish from nighttime predators like moray eels, which hunt by their sense of smell.

Region: Philippines

The parrotfish get their name from their beak-like teeth and wildly bright colors, like parrots. Up to 3 feet (90 cm) long, the bicolor parrotfish is the largest parrotfish on the reef. Parrotfish go through different phases in their life and changes color in each phase. Starting as a juvenile, this parrotfish has a white body, orange head with a lighter orange color near the mouth. The fins are a light brown. Then they enter the initial phase as a male or female and are relatively drab in color. Females have a two-toned body. The top half is yellow and the scales on the bottom half of the body are green with black tips. Most of the female’s head is light grey color and the small region under the mouth is almost black. The fins are black as well. The colors of the supermale are brighter. The scales on the body are green with pink tips and the head is green with pink spots. The fins are a mix of pink, purple, green and blue. In the region under the mouth, there is a green band with an area of pink underneath. Initial phase males are much smaller than supermales and they have muted coloring. In all three phases, these parrotfish have bright orange eyes.

Swimming on clear lagoon and seaward reefs, bicolor parrotfish dive down to depths of 100 feet (30 m). The juveniles swim alone, but the adults are found in small groups. Terminal phase males always live in a certain area, defending a particular territory.

These parrots live in the warm waters of the Pacific Ocean, Indian Ocean and the Red Sea.

A parrotfish eats the algae that grow on and around coral, biting off bits of coral skeleton with its strong, bird-like beaks. The beak is actually made of individual teeth that are fused together to form a structure like a beak. If you look closely at one, you can see the different teeth closely packed together. After biting off a chunk of algae-covered reef, pharyngeal teeth or powerful molar-like teeth in the throat, crush the hard limestone rocks. The fish’s small, stomach-like pouch extracts nutrients as it digests algae. When coral rock has traveled all the way through the fish’s system, it comes out as the silky sand we see on many beaches. Waves and currents carry this sand to shore, where it helps build the beach.

Parrotfish constantly search the reef for algae to eat. As a result, a large parrotfish like the bicolor parrotfish can produce up to 2,200 pounds (1 metric ton) of sand per year.

Parrotfish start their lives either as a male or a female, just like any other fish. But they can also change sex. These fish are protogynous hermaphrodites, which means they can start their life as a female and then change to the male. Parrotfish are born with both male and female sex organs.

After parrotfish become adults, they are called initial phase males or females. Those that were born male will always remain as an initial phase male and will never have a chance to be a dominant male. Some of the adult females will change into males. These males and the remaining females are also called initial phase parrotfish. But some of the larger females will become supermales. This most often happens when a supermale dies. The supermale is larger than all the other males and has distinct colors and patterns on its skin. This coloration attracts the females to the supermale. Sex change in parrotfish ensures there will always be a male to reproduce with all the females.

The few supermale parrotfish on the reef sport brilliant hues to attract all those females. Initial phase males are different from the supermales. When courting the females, the color of all the males will actually become brighter and more brilliant.

Spawning happens at dusk. A supermale mates and spawns with its harem or small group of females. Most adult bicolor parrotfish are initial phase females and males. Since there are so many, initial phase males gather together with large groups of females to spawn. Whether they are terminal or initial phase males, the parrots will pelagic spawn, which means they will all gather in an area where the fertilized eggs will be taken away on the currents to drift into the open ocean. This ensures the species will be found in a wider range of areas. Once the eggs hatch, the larvae remain in the epipelagic zone or the zone in the open ocean near the surface. When the larvae reach about 5 to 6 inches (12 to 15 mm) long, they become juveniles and swim down to join the reef ecosystem.

>A species or group of organisms that is in danger of extinction or disappearing from the face of the earth in the near future if its situation is not improved.

A species that can be found throughout its natural range but is declining in number and may become endangered in the absence of special protection efforts.

A species that is not declining in number but is of special concern because it is sensitive to pressure by particular human activities or natural events.

A species that is not declining in number and is not sensitive to pressures by human activities or natural events.

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Threats and Management
Because of their large size, bicolor parrotfish are sought after for their meat. Fishing efforts seem to have been under control as the population of these parrotfish have not decreased throughout their range.

Did You Know?
Parrotfish are difficult to keep in aquariums since they need to constantly graze on dead coral rock in order to keep their teeth from growing too long. Home aquariums often do not grow enough algae to support parrotfish. Without the chance to scrape off algae, the beak of the parrotfish will continue to grow.

Parrotfish evolved from the wrasses and share many of their characteristics, like reproduction. These two groups demonstrate differences in their teeth, digestive system and eating habits.

Web Sites:
NOTE: The following Web sites are not maintained by the John G. Shedd Aquarium and will open in a new browser window.


Print Publications:
Debelius, H. 1999. Indian Ocean Reef Guide. Frankfurt, Germany: IKAN. 321p.
ISBN# 3-9317-0267-7.

Myers, R.F. 1999. Micronesian Reef Fishes. Barrigada, Guam: Coral Graphics. 216p.
ISBN# 0-9621564-4-2.

Perrine, D. 1997. Mysteries of the Sea. Lincolnwood, Illinois: Publications International, Ltd. 312p. ISBN# 0-7853-2430-5.

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Vocabulary Words

Epipelagic zone – The zone of the open ocean near the surface.

Extinction – An organism that has not been present on the face of the earth for over 50 years.

Harem – A group of females that mate with one male.

Hermaphrodite – Having the sexual organs of both male and female; able to produce both egg and sperm.

Initial phase – The first phase of a certain fish, like parrotfish , after the juvenile stage. These initial phase fish are female or they may change to smaller males. The initial phase female is drab in color.

Organism – A living thing.

Pelagic spawners – Fish that gather in an area in the ocean where the fertilized eggs will be taken away on the currents to drift into the open ocean.

Pharyngeal teeth – A powerful set of molar-like teeth in the throat of fish used to for grinding.

Protogynous – Starting life as a female then changing into a male.

Seaward – Closer to the open ocean than the shore.

Species – A group of organisms capable of breeding and producing fertile offspring; organisms that share the same gene pool.

Supermale – The final phase of a parrotfish or parrotfish. The female fish metamorphoses into a male and the coloring is brilliant and bright.

Territorial – An animal that lives in the same area all the time. This animal reproduces in this area and fiercely defends it.

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Bicolor Parrotfish
Bicolor Parrotfish

Bicolor parrotfish (Cetoscarus bicolor) Copyright Shedd, Edward G. Lines
Bicolor parrotfish (Cetoscarus bicolor) Copyright Shedd, Edward G. Lines

Bicolor Parrotfish 3
Bicolor Parrotfish 3

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