Humphead parrotfish

humphead-parrotfish

Humphead parrotfish

Humphead parrotfish (Bolbometopon muricatum) is also known as bump-head parrotfish or green hump-head parrotfish. It grows up to 1.3 meters and can weigh up to 46 kilos which makes it both the largest and heaviest of all parrotfish species. 

They grow slowly and their life spam is about 40 years.

Fun Facts about humphead parrotfish

bumphead-parrotfish

The reason for its name is the prominent hump on their foreheads, which develops as they mature.

In fact, they use this hump to break off pieces of hard coral for their digestion.

The hump can also use it in “head-butting” contests for a chance to mate or control the school.

Another extraordinary characteristic of these fish is their mouths. In fact, they have no one, but two sets of teeth. For instance, big front teeth fused in the shape of a beak and pharyngeal teeth at the back of their throat.

The parrotfish’s teeth are composed of ­fluorapatite, among the ­hardest biominerals in the world. This makes the parrotfish’s teeth harder than ­copper, gold and silver.

Diet

Green parrotfish are omnivores. In fact, they feed on coral and algae as well. This makes them different from other oceanic species.

humpead-parrotfish

Coral is a very hard solid substance and takes a special mechanism to be eaten. That’s why Humphead Parrotfish don’t have much competition for food.

They extract the algae from chunks of coral ripped from a reef. The parrotfish grind the coral into a hard paste, extracting what they love most, the algae. The hard material that does not provide nutritious food for them is pulverised and passed like feces. Yes, they poop sand. 

Behaviour

Adult Humphead parrotfish like swimming mostly in schools during the day to feed. They can group up to 75 or more.

In the other hand, young parrotfish stay back in the grassy seabeds closer to home and away from possible predators.

Sleeping time

At night, humphead parrotfish create a bubble around themselves while they rest. The cocoon is made of mucous secreted from an organ on their head. The cocoon masks their scent, making it harder for nocturnal predators to find them.

Reproduction

marine-life-bali-humphed-parrotfish

A School of parrotfish is led by a dominant male. When it dies or leaves the group, other parrotfish will take the place by switching genders. In truth, a secondary male can become female or become a primary male.

Parrotfish can change sex multiple times in a lifetime.

Reproduction occurs once both sexes reach sexual maturity.  For males it happens when they are 5-7 years old, while for females is a little bit slower, reaching maturity when they are 9 to 11 years old. 

Spawning can occur throughout the year if conditions are stable and productive. Courtship and spawning happen during early morning in a protected area. Females release eggs that are fertilised by the sperm circulated in the water by the male humpheads. The eggs are usually hidden in plants that help to protect and camouflage the eggs from being eaten by predators. After they hatch the newly-hatched offspring stay in this secluded area for up to a year to grow and mature before joining the adults in the reefs.

Green Humphead Parrotfish plays a very important part in the environment

Corals and parrotfish have a mutualistic relationship. While  parrotfish gets its food by feeding on corals, the coral also benefits because the parrotfish is eating off the algae that are growing on it. By eating the algae off the coral, keeps the algae from taking over the coral reefs.

diving-tulamben-liberty-wreck
School of humphead parrotfish at Tulamben, Bali

They eat a lot! A humphead parrotfish eats approximately five to six tons of corals per year. Even more, they produce enough sediment to create new reefs, distribute  more sand, and also influence the structure of current reefs and spawn new coral reef ecosystems.

Threats

Some sharks and humans are the only predators of humphead parrotfish. 

Commercial fishing as well as spearing fishing have made a huge impact in decreasing the population of this fish.

Unfortunately, they are routine in mating and other habits as well. In other words, since humphead parrotfish like to school in large numbers and use predictable sleeping sites in shallow waters, it makes them easy to harvest for food.

Where can we see humphead parrotfish in Bali?

Humphead parrotfish is a common fish in Bali and you can see them all along the coastline.

But if we have to choose one dive site to see them, that would be, no doubt, the USAT Liberty Wreck in Tulamben.

Humphead parrotfish have found their home and protection at the wreck. In truth, they come to sleep inside the wreck every night. At sunrise, humphead parrotfish get out of the wreck, and gather together to go for their daily swim. 

Both sunrise and night dive at the Liberty wreck is the perfect time to see these unusual and unique looking fish in Bali.

Be a responsible diver

Always follow the code of conduct of a responsible diver. Control your buoyancy and also remember do not touch anything underwater. To sum up, just take photos and leave only bubbles!

Special consideration at night diving with humpheads. Do not disturb the fish while sleeping. And also be careful with your underwater light and never flash it directly on the fish’s eyes.

Learn more about marine life in Bali

Would you like to dive with us? Send us an email to southerndreamsdiving@gmail.com