Bleaching in the world's reefs over the past couple of years is immediately evident from the stark images of corals shedding their myriad colours for a ghostly white.

While as much as half the corals of the Great Barrier Reef died during the marine heatwaves of 2016 and 2017, researchers are only now beginning to assess the toll on the many species that rely on corals for food and shelter.

"A lot of the attention is on the corals," Marian Wong, a marine biologist from the University of Wollongong, said. "The public's perception is that the fish are mobile enough to just swim away."

Researchers at Lizard Island on the Great Barrier Reef are studying the impacts of coral bleaching on fish and anemones that depend on them. Credit:University of Wollongong

In fact, clownfish - made famous by the Finding Nemo film - and other species such as coral goby fish "are just terrible swimmers, designed to sit in their little spot their whole lives", she said.