Pale in front, black behind, hovering in pairs over rubble in a little current.
A dartfish to about 14 cm, sharply two-toned: the front third of the body pale blue-grey, the rear abruptly blackish-blue, with black dorsal and anal fins and a deeply forked tail. The transition is not a bar but a broad gradient, and no other Ptereleotris here is coloured this way. Ptereleotris zebra is barred in orange along the whole body; Ptereleotris grammica is pale blue with yellow lengthwise stripes and lives deeper on rubble. Juveniles are darker overall with a whitish tail and are often in larger groups than the adults.
Hovers head-up a half metre or more above the bottom, usually in pairs, taking zooplankton from the passing water. Each fish keeps a burrow or a hole in the rubble below it and drops into it head-first when pressed, which is the whole behaviour of the family: hover, feed, drop. It reappears within a minute or two if nothing further happens, and then rises gradually rather than in one movement.
Recorded from about 3 to 30 m along reef edges, drop-offs and rubble slopes where there is some water movement, so it is a fish of the margins of a muck site rather than the open silt. The usual approach is to note the hole, settle at a distance and wait out the first retreat rather than to close on the fish while it is still up in the water.
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.
