Dark brownish with one pale streak from eye to lower pectoral base and another short one above gill opening. Lower part of head and abdomen dark blue or purplish. Caudal fin brownish yellow, broadly edged in white. Small juveniles are dark brown above and white below with a dark horseshoe-shaped mark on the tail
Dorsal fin with 3 spines and 26-28 rays. Anal fin with 23-26 rays. Pectoral fin with 12-14 rays.
Deep groove before eye. Longitudinal rows of small spines following scale centers on about posterior third of body. Dorsal and anal fins slightly elevated anteriorly. Caudal fin truncate to slightly rounded with acute corners.
Halfmoon triggerfish's facts
Did you know?
Triggerfish have a hard spine Dorsal Fin that can be locked.
When sleeping this spine is used to wedge them into place in a crevasse and so deter predators from pulling them out of their bed!
The spine is also held erect as a warning to other fish to stay away.
Halfmoon triggerfish's Behavior & Ecology
Widespread Indo-Pacific. Inhabit coastal to outer reefs. Habitats from silty lagoons to pristine outer reef walls. Occur in shallow lagoon and seaward reefs. Solitary and territorial.
Halfmoon triggerfish's Feeding
They feed on a wide range of food items, including live coral, algae, sea urchins, crabs, molluscs and other invertebrate groups as well as fish and sea squirts.
Halfmoon triggerfish's Reproduction
Male defends a defined territory, within which a female resides. On the day prior to spawning, female pushes her snout into the sandy bottom repeatedly and removes small stones and pieces of coral at several sites. Adhesive eggs are deposited on the sandy bottoms or in a small cavity of the reef covered with sand. Female fans the eggs and defends the nest, while male patrols around female. Females are territorial, solely tending and guarding the eggs . Males exhibit polygyny