The solitary duckbill eel (Nettastoma solitarium) is an eel in the family Nettastomatidae (duckbill/witch eels). It was described by Peter H. J. Castle and David G. Smith in 1981. It is a marine, deep-water-dwelling eel which is known from the Indo-Western Pacific, including KyushuâÂÂPalau Ridge, the Philippines, Australia, and the Hawaiian Islands. It is known to dwell at a depth range of . Males can reach a maximum total length of .
The species epithet "solitarium", meaning "solitary" in Latin, refers to the species' wide and isolated distribution in the Pacific.