A fibreglass cast of a big ocean sunfish was made in 1960 and has long been on display at the museum, at present in the ground-floor foyer.
However, the mysterious fish had, in effect, been hiding in plain sight for decades, as a member of a previously unnamed and undescribed sunfish species.
And it was only a few years ago, in 2017, and thanks to some genetic detective work, that the sunfish was given its correct name.
Scientists identified it as a newly named hoodwinker sunfish (Mola tecta), a member of the first new sunfish species to be identified for 130 years.
Hoodwinkers are found in the cold waters of New Zealand, southern Chile, South Africa and the southeast coast of Australia and may be relatively common in New Zealand waters.
The museum’s cast records the largest known member of the hoodwinker species, which may have weighed about 450kg.
Sunfish, sometimes likened to a ‘‘giant pancake’’, are the world’s heaviest bony fish. They can weigh up to two tonnes and reach 3m in length.
Museum visitor experience and science engagement director Dr Craig Grant said the covering on the hoodwinker fish was not yet another fishy disguise from the maritime master.
Rather, the move reflected an effort by museum staff, at Alert Level 2, to prevent any accidental transmission of Covid-19 through people touching the cast.
The fibreglass was more difficult to keep clean than metal and other surfaces, which were repeatedly cleaned as a precaution each day at the museum, he said.
