The male displays for about forty minutes before sunset and is dull for the rest of the day.
To about 10 cm. Females are plain orange-pink. Males are red-orange with blue lines along the flanks, a yellow belly and several filaments extending from the dorsal fin. In display the male turns intensely blue and magenta, spreads every fin and swims a short rapid arc, then reverts within a second or two; the colours shown in display are not present at any other time.
Displaying happens in the last half-hour or so before sunset, over rubble slopes where a group of one male and a dozen or more females feeds on zooplankton. It is one of the few reef subjects where the photograph depends entirely on timing rather than on finding the animal: the fish is present all day and worth photographing for a few minutes of it. High shutter speeds and pre-focusing are the usual approach, since the display is over before a camera can be aimed at it. Recorded from about 5 to 35 m.
Ratings are per location: 1 means found on most dives that look for it, 5 means a handful of records. Where enough dives have been logged the figure is calculated from them; otherwise it is an editorial estimate, and says so. We publish habitat and destination, not the dive site.