The yellow and blue-back fusilier or Caesio teres is a fish classified in the class Actinopterygii, order perciformes and family Caesionidae. It is a widely distributed species and common in all tropical regions of the Indian and Pacific Oceans, from the African coasts (except the Red Sea and the Persian Gulf) to the Line Islands (Kiribati). It inhabits the waters near coral reefs, with a preference for coral lagoons.
The body of Caesio teres is fusiform in shape and laterally compressed. It can reach sizes up to 40 cm in length. In his face stands out the large size of his eyes, and a small terminal mouth equipped with small and numerous teeth both in the jaws and in the vomer and palatines. It has a single dorsal fin formed by 10 spines and 15 soft rays, although on rare occasions we find specimens with 14 or 16 soft rays. The anal fin is formed by 3 spines and 12 (rarely 13) soft rays. The pectoral fin has 20-22 rays. As for the color of Caesio teres, it is mostly silvery-blue with a bright yellow stripe running along the back two thirds of the dorsal area, from the middle of the dorsal fin, to the caudal fin, completely covering the entire caudal peduncle. The pectoral, pelvic and anal fins are silvery white, while the dorsal fin is bluish proximally and yellowish distally.
Caesio teres is a gregarious fish, usually found in large schools of individuals in coral lagoons. It is common to observe specimens of Caesio teres grouped with other species of fusiliers such as Caesio xantonota. It is a species that moves quickly, covering large areas between reefs where it feeds on zooplankton.
The reproduction of Caesio teres always coincides with the full moon, when large groups of specimens gather to spawn together. After fertilization, the eggs become part of the plankton for a short period. These eggs are spherical and completely translucent, lacking any pigmentation. After a few days, the fry hatch and are dispersed by the action of currents.
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