what makes sergeant fish easy to recognise?

The sergeant fish, specifically the sergeant major (Abudefduf saxatilis), is easy to recognize by its distinct features: it has a small, flat, oval-shaped body with five prominent vertical black bars on its sides that resemble military sergeant stripes. Its coloration includes a silvery-gray body with a yellow sheen along the upper sides in its light phase, while in the dark phase (often when hiding in crevices), its body darkens to bluish-gray, almost blending with the bars. It also has a small terminal mouth and a black spot at the upper base of the pectoral fin. The fish's compressed oval shape, the five vertical black bars, and the color phases make it distinctive and easy to identify in its reef habitat.