Appearance
As its names suggest, it is pale yellow with numerous small dark spots. There is also a black bar extending above and below the eye and a black margin to the anal fin. The largest recorded specimen was 13 centimeters (5.1 in) long.
C. citrinellus is common in shallow exposed reef flats, lagoons, and seaward reefs, generally in relatively open areas with scattered corals. They may occasionally be found at greater depth, as deep as 36 meters (118 ft). They feed on small worms, small benthic invertebrates, coral polyps and filamentous algae.
Adults usually swim in pairs (pairs form during breeding), while juveniles are more often seen in small aggregations and commonly mix with other similar sized juveniles, especially of the Sunburst Butterflyfish (C. kleinii). They are oviparous.