A ribbon eel in yellow (female) phase.  Examples of blue males are in Indonesia/Komodo

section.  Example of black juvenile is in Indonesia/Ambon section.

(Aer Prang, Lembeh Strait, Sulawesi, Indonesia)

fish; eel; moray; ribbon eel; female; yellow phase; Chordata; Osteichthyes; Anguilliformes; Muraenidae; Rhinomuraena quaesita, South Pacific