The yellow moray is the moray eel most likely to introduce itself. Unlike its relatives, which tend to maintain a degree of crevice-based reserve, Gymnothorax prasinus is described by divers as inquisitive, and can occasionally be approached and even handled with reasonable care. This does not mean it lacks opinions. It means its opinions are expressed differently, and on a longer timeline, than most reef fish. New Zealand's most common moray eel, the yellow moray is confined to the North Island from North Cape south to roughly the Māhia Peninsula, and prefers inshore coastal reefs over the exposed outer islands where its relatives the mottled and grey morays are more reliably found. The colouring ranges from yellow-green through dull gold to yellow-brown, the head typically orange, and some individuals carry strikingly blue eyes. The body is elongate, muscular, scaleless, and covered in a mucous layer that gives it a faint fluorescence against dark reef backgrounds. The mouth extends well behind the eye and is lined with backward-curving teeth designed to grip rather than cut. The open-mouthed posture that divers sometimes find alarming is not aggression. All morays breathe by pumping water across their gills via the mouth, because the gill openings are too small to ventilate through alone. The expression this produces is a design outcome, not an invitation. At night the eel leaves its crevice and moves across the reef in search of crabs, urchins, and small fish. Telemetry research in New Zealand found that yellow morays use a consistent home range of roughly 0.15 to one hectare but do not necessarily return to the same hole each day, shifting between several suitable crevices across seasons. A noted behaviour is the use of cleaner shrimp. Yellow morays have been observed allowing small shrimp to enter the mouth and move carefully across the teeth, removing parasites and food debris. The eel holds still for this. The shrimp appears to know the arrangement is reliable. It is one of the more improbable working relationships on a New Zealand reef and seems to suit both parties well. No population estimate exists for New Zealand. The species is not threatened, not commercially targeted, and not formally assessed. It is simply present on northern inshore reefs, doing what morays do, in the same holes and the same general neighbourhoods it has occupied for a long time. The reef changes slowly. So does the moray's schedule.