Caesio
Caesio is a genus of fish belonging to the family Caesionidae, commonly known as fusiliers. They are distinguished by their vibrant colors, slender bodies, and gregarious nature, forming large schools in the clear waters of coral reefs. These fish are widely distributed across the Indo-Pacific region, inhabiting tropical and subtropical waters.
Common Names
Members of the Caesio genus are commonly called fusiliers, a name shared with other members of the Caesionidae family. Depending on the species, they may also be referred to as "yellowtail fusiliers", "redbelly fusiliers", or "blue-lined fusiliers", among other regional names.
Characteristics
Fusiliers are characterized by their elongated, fusiform body shape, resembling a torpedo. They typically have a silvery-grey base coloration with striking color variations, often exhibiting vibrant yellow, orange, or red hues on their flanks and fins. Some species have distinct dark stripes or bands along their bodies, while others display iridescent scales that shimmer in the sunlight.
Their mouths are small and protrusible, adapted for feeding on zooplankton and small invertebrates. Fusiliers possess a single dorsal fin with a distinct notch separating the spiny and soft-rayed portions, as well as a forked caudal fin. They are generally small to medium-sized fish, ranging from 15 to 50 centimeters in length.
Environments
Caesio species are primarily found in shallow, clear waters associated with coral reefs. They favor areas with abundant coral cover and a high density of zooplankton, their primary food source. Fusiliers are highly social and often congregate in large schools, numbering hundreds or even thousands of individuals. These schools can be seen traversing the reef slopes, feeding, and occasionally darting through the water in unison.
References
For further information on the Caesio genus and its species, consult the following sources: