Operculum (fish) Operculum (fish) The operculum is a series of bones found in bony fish that serves as a facial support structure and a protective covering for the gills; it is also used for respiration and feeding. The opercular series contains four bone segments known as the preoperculum, suboperculum, interoperculum and operculum. The preoperculum is a crescent-shaped structure that has a series of ridges directed posterodorsally to the organisms canal pores. The preoperculum can be located through an exposed condyle that is present immediately under its ventral margin; it also borders the operculum, suboperculum, and interoperculum posteriorly. The suboperculum is rectangular in
Upeneus moluccensis anal fin. The caudal fin is deeply forked. The chin bears a pair of barbels which do not extend past the margin of the preoperculum. The upper and lower jaws, the palatine and the vomer are covered in brush-like or villiform teeth. The back is pinkish-red in colour contrasting with the white belly, from which it is separated by single longitudinal yellow stripe which runs from the operculum to the caudal fin peduncle. The dorsal fins are yellow in colour with 3 parallel red bars while the pectoral find is a similar colour but lacks markings and the pectoral fin