Humans have always been drawn to the weird and unusual and the ocean sunfishes (Family Molidae) are no exception. For hundreds of years they attracted the keen attention of naturalists and ichthyologists, who recorded their encounters in fantastical drawings and descriptions, wondering what kind of species they had in front of them. The sunfishes still attract our attention today, in a time of torrential Twitter feeds and easy information sharing. So how could a massive species of ocean sunfish escape detection and recognition all this time? Join me on a guided tour of fish forensics, starting in the surf of New Zealand where a stranded giant threw the case wide open, through the genetics lab and eerie museum vats, and onwards through dusty pages of old Latin biology books featuring merman and sea monsters, to the final conclusion that forgotten taxonomic confusion and human circumstances enabled one of the world’s giants to hide right in front of us – in Australia, New Zealand and beyond.