Black as a juvenile, blue as a male, yellow as a female, in that order.
A moray of very different build from the rest of the family — long, laterally compressed to the width of a ribbon, with a high dorsal fin running the length of the body, expanded leaf-like nostrils and three short barbels on the lower jaw. It reaches about 130 cm, of which a diver usually sees the front third, the rest being in the hole.
The colour sequence is the interesting part and the source of most of the confusion about it. Juveniles are jet black with a yellow dorsal fin; as they mature they turn blue with a yellow snout and dorsal, and these are males; larger animals turn entirely yellow and are females. The species is a protandrous hermaphrodite, so a blue eel is a male that was black and may become yellow — three colours, one species, and not three species as older sources have it. Yellow animals are much less often seen than blue. Occupies a burrow in rubble or sand at reef margins and holds the same hole for long periods, swaying clear of it with the mouth open.
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.
