Blue tangs are herbivorous as adults, feeding largely on filamentous algae. They avoid eating calcareous material, like corals, because they lack the gizzard-like stomach of other surgeonfishes. Acanthurus coeruleus individuals feed singly, in small groups, or in large aggregations numbering over 100. Large aggregations can and in these groups can ravish damselfish gardens on reefs. Blue tangs that live in smaller populations do more foraging in the water column. Blue tangs will also eat plankton.
Animal Foods: zooplankton
Plant Foods: algae; phytoplankton
Primary Diet: herbivore (Algivore)