Giant leptocephalus
The giant leptocephalus is a species of eel in the family Notacanthidae. It was first described by Peter Henry John Castle in 1959. It is a marine, deep-water dwelling eel which is distributed worldwide.
If it is indeed a leptocephalid, it is probably the larvae of a Notacanthus species, most probably Notacanthus chemnitzii. In 2014 it was confirmed as a species of Coloconger.