The rarely seen and elusive fish are the largest bony fish species in the world and have a distinctive flattened appearance.
Helen O’Neill of CSIRO’s Australian National Fish Collection (ANFC) said adults of Mola mola, the Ocean Sunfish, the largest of the five sunfish species, can grow to more than three metres in diameter and weigh up to 2500 kg.
"Sunfish swim in solitary out in the open ocean following ocean currents but occasionally enter coastal areas," Ms O'Neill said.
"Sometimes they are unable to find their way back to the ocean and become trapped in shallow waters, eventually washing onto the beach.
"We are collecting tissue samples from some of the beached specimens, despite the specimens smelling terrible and containing maggots.
"The samples are extremely valuable to science, they will allow us to confirm the species of sunfish, and will be added to the existing collection of genetic data held at the ANFC, which can be used for future research."
The genetic samples join 21,000 other genetic samples of fish held at the ANFC in Hobart.
The collection was founded in 1943 and today houses 160,000 fish specimens for research.
They represent 3,700 species, comprising mostly sharks, rays and deep-water fishes from Australia, Antarctica and the Indo-Pacific region.
Read more about the ANFC.