Like other members of its family, it has characteristic 10 dorsal soft rays, 9 dorsal spines, 9 anal soft rays, and 3 anal spines,[3] It is found in Indo-West and Central Pacific, from the Red Sea, north to Japan, south to Australia and east to French Polynesia.

[3] The dusky parrotfish feeds primarily on algae found on hard substrate and dead coral.

In aerobic conditions, bacteria ferments the carbohydrates and produces short-chain fatty acids or SCFAs.

[7] The presence of the swarthy parrotfish in large and small reef communities contributes to diversity and therefore the resilience of the ecosystem.

After extreme climate events, like cyclones, subtle reef dynamics change such as grazing by herbivorous fish.

In 2011-2012, after severe climate disturbances, grazing by herbivorous fish, including the swarthy parrotfish, decreased by over 90%.