Indo-Pacific Sergeant

The Indo-Pacific sergeant (Abudefduf vaigiensis) represents a pomacentrid fish species endemic to the Indo-Pacific region. Commonly mistaken as the Sergeant major, the designation is traditionally attributed to the species Abudefduf saxatilis. The related species Abudefduf caudobimaculatus was previously regarded as conspecific; however, particular taxonomic authorities continue to debate its synonymy.

This species occupies a vast geographic range, spanning the Indo-Pacific from the 🌊 Red Sea to the western and central Pacific regions, including the Mediterranean Sea, where it is believed to have been introduced through the Suez Canal (🇪🇬 Egypt). However, the exact distribution in the Mediterranean remains ambiguous, potentially due to taxonomic confusion with Abudefduf saxatilis and Abudefduf troschelii.

Morphologically, Abudefduf vaigiensis exhibits a white bluish hue with a yellow upper body and a distinctive black spot near the dorsal fin. The fish's dorsal features comprise 13 spines and 11 to 14 soft rays, while the anal fin comprises 2 spines and 11 to 13 soft rays. Maximum recorded length is 20 centimeters, with maturation occurring at approximately 12 centimeters. Notably, males display a more intense blue coloration during the spawning period.

The diet of the Indo-Pacific sergeant consists primarily of zooplankton, benthic algae, and diminutive invertebrates. Adult specimens commonly inhabit coral reefs, tide pools, and rocky reefs, while larval stages are pelagic. Diverse ecosystems welcoming this species include tropical and subtropical waters at depths ranging from 1 to 15 meters.

Social behavior of the Indo-Pacific sergeant involves formation of substantial aggregations, where individuals either engage in midwater foraging or nest activities. Additionally, reports have emerged citing instances of Ciguatera fish poisoning associated with the consumption of this species.

Reproductive patterns consist of the male's nest construction within rock or coral structures, followed by the female depositing the eggs, which are subsequently fertilized by the male. In their paternal role, males are responsible for guarding and ensuring proper aeration of the eggs until hatching ensues.