Hovers in loose groups over clean sand and disappears into it head-first when pressed.
An extremely slender, almost translucent sand-dweller to about 18 cm, pale sandy grey with fine darker speckling, a long low dorsal fin running most of the back and eyes set high on a pointed head. Males are larger, more strongly marked with dark blotches along the flank, and carry the first few dorsal spines drawn out into free filaments that are raised in display. Females and juveniles are plainer and easily taken for something else entirely. A second species, Trichonotus elegans, occurs across much of the same range and is separated on fin-ray counts and on the number and length of the male dorsal filaments; photographs of hovering fish frequently cannot be taken to species, and records under either name should be read with that in mind.
Hovers in loose aggregations from a few centimetres to half a metre above clean, well-sorted sand, usually where a little current runs across the slope, feeding on small zooplankton carried past. When a diver closes, the whole group drops and enters the sand head-first, vanishing without a trace, and individuals surface again a few metres away after a minute or so; the fish also sleeps buried. Recorded from about 8 to 35 m, and largely absent from silt, since the burying behaviour needs clean loose grains. Approaching one directly almost always empties the patch, and most photographs of the species are made by settling at a distance and waiting for the group to drift back rather than by swimming towards it.
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.