The Bullethead Parrotfish (Chlorurus sordidus) is also known as the Daisy Parrotfish. They are probably the most common species of parrotfish in Tanzanian waters. As with all the parrotfish there is considerable divergence in looks between juveniles and adults.
To make it even more difficult there are regional variations and some females change into males which are very brightly colored. These are known as Supermales. Parrotfish obtain their name from their teeth which in most species are formed into a beak.
The juvenile Bullethead Parrotfish resembles a cardinalfish and has a series of black and white horizontal lines across it. The initial phase, pictured below have a dark rear body with a light green colored head. There are six to eight white dots in pairs on the rear of the body. They have the ability to turn these dots on or off.
As they mature into terminal phase males so the body goes a blue green colour as pictured above with a light blue lower jaw and pink lines around the mouth. The coloration can vary considerably between individual specimens. They grow up to 40 cm in length. They are fairly easy to distinguish from other parrotfish by the bullet shaped head.
BULLETHEAD PARROTFISH IN THE WILD
The Bullethead Parrotfish are common on the reefs of Tanzania. The initial phase females form groups and feed across the reef with goatfish and wrasses. The more colourful males will often join these groups but tend to swim a much wider area.
We have witnessed fights over territory or groups of females. Two males approach each other and then dart at each other, each grabbing the others beak. With beaks locked the two then jostle for control , each trying to twist the other. The stronger fish is able to twist the hardest and the smallest fish backs off and lets go, swimming away.
Despite the fact that it appears to be quite dangerous because of their powerful beaks, neither male seems to be physically harmed from the confrontations and no biting attempts seem to be made other than to jaw wrestle.
The Bullethead Parrotfish(Chlorurus sordidus) is found across the western Indian Ocean. In the eastern Indian Ocean and Pacific, Chlorurus spilurus a very similar but genetically different species takes over. They are found mainly on the slightly deeper reefs from 12 meters downwards, but are occasionally seen on shallower reefs from 1 meter downwards.
The Bullethead Parrotfish feed on a variety of algae and sea grass. They use their powerful beaks to scrape algae off of coral.
Parrotfish are unusual in that they have the ability to change their sex throughout their lifetime. At birth both males and females are present and these are referred to as primary males and females. The primary males and females are less colorful and are often difficult to tell apart. Secondary males are born female and change their sex when prompted by social cues such as the absence of another secondary male. These secondary males are often referred to as Supermales because of the brightness of their colors.
Individual pairing takes place and the eggs are released into the substrate. Males form harems and protect these from other males. Mating takes place between individuals.
Bullethead Parrotfish are not commonly kept in aquariums although some public aquariums may occasionally keep them for public display. This is both a function of their size and the difficulty in providing them with food.
All the Parrotfish are heavily exploited in Tanzania both by trapping and netting. A specimen can be seen trapped above. Parrotfish carry a heavy premium on price, particularly blue colored parrotfish. They make very good eating.