Climate change is dulling the hearing of fish and making it more difficult for them to find a home, Australian researchers say.

More carbon in the atmosphere means less calcium in the water and consequently poorer hearing in fish, who use hearing as much as sight to locate a habitat.

James Cook University researchers Monica Gagliano and Martial Depczynski says tropical fish on the Great Barrier Reef, off the east coast of Australia, are growing asymmetrical ears.

Increasing acidity has cut the calcium carbonate that fish need to grow healthy bones including ear bones, the researchers said. The higher acid levels makes it more difficult for fish to absorb calcium.

'If their hearing is compromised because they have asymmetry ...it's going to affect their ability to navigate back to the reef and they'll just get lost in the open ocean,' Depczynski told Australia's ABC Radio.

Gagliano said that 'ear bone asymmetry in the early life stages of reef fish interferes with their capacity to find and settle on coral reefs'.