[4] This species is known to be predated on by the honeycomb grouper (Epinephelus merra) and the coral trout (Plectropomus leopardus), its parasites include the monogenean Benedenia scari.

[5] Chlorurus sordidus is one of the most widespread species of parrotfish, and it is highly variable with some of the geographically determined forms probably being at least subspecies.

The juveniles and females in their initial phase form large groups that move long distances between their feeding grounds and the areas used for sleeping at night.

[2] Chlorurus sordidus has been split by some authorities and the Red Sea dn Indian Ocean populations are regarded as C. sordidus while Chlorurus spilurus occurs in the Pacific and Eastern Indian Ocean, this is based on mitochondrial DNA sequencing and on morphological data.

[1] Scarus sordidus was described by the Swedish explorer, orientalist and naturalist Peter Forsskål (1732-1763), the description was published in 1775 with the type locality being Hurghada in Egypt.