Yellowback Fusilier

The Yellowback Fusilier (Caesio xanthonota) is a pelagic marine ray-finned fish, classified within the family Caesionidae. This species is indigenous to the tropical Indo-Pacific region, typically inhabiting shallow waters ranging from the East African coast to 🇮🇩 Indonesia.

The species was first described in 1853 by the Dutch ichthyologist Pieter Bleeker, with Batavia on Java noted as the type locality. Within taxonomic classification, the Yellowback Fusilier has been assigned to the subgenus Flavicaesio. The specific epithet "xanthonota" derives from the Greek words "xantho," meaning "yellow," and "nota," meaning "back," referencing the species' distinctive yellow upper region.

As a small to medium-sized fish, the Yellowback Fusilier can grow up to approximately 40 cm (16 inches) in length. The fish features a small, terminal mouth capable of protrusion to facilitate consumption of food. The body assumes a fusiform or spindle shape. The dorsal fin is supported by 10 spines and 14-15 soft rays, while the anal fin comprises three spines and 11 or 12 soft rays. The caudal fin exhibits a deeply forked structure. Body coloration is predominantly greyish blue, with a prominent bright yellow band spanning from the forehead, between the eyes, to the tail, encompassing the dorsal and caudal fins. This yellow region generally covers the upper third of the body, while the belly remains plain white.

Caesio xanthonota is extensively distributed across the tropical waters of the 🌊 Indian Ocean, excluding the 🌊 Red Sea and 🌊 Persian Gulf, and extends to 🇮🇩 Indonesia in the western 🌊 Pacific Ocean. It occupies mid-water zones in deep lagoons and near external reefs, residing at depths of up to 50 meters.

The species primarily feeds on zooplankton, classifying it as a planktivore. The Yellowback Fusilier is diurnal, exhibiting social behavior by forming groups and schools alongside other caesionid species, such as Caesio teres.