One of the most hideous beasts in Australia may be getting a whole lot uglier.

A Queensland researcher says numbers of mutant cane toads, with extra legs, eyes and toes, are becoming more common in Gladstone.

Scott Wilson, from Central Queensland University, says that while mutations generally occurred in one per cent of cane toads, abnormalities were consistently being found in six to eight per cent of specimens in Gladstone, the city at the heart of the country's gas boom.

Dr Wilson said a link to recent mutations in fish in Gladstone Harbour could not be ruled out, although it was unlikely.

Toads are freshwater animals, but Gladstone Harbour is fed by rivers and streams.

"Obviously the fresh water flows down to the sea, so there's potential for things to occur in that regard," he told AAP.

"We can't really say for sure, of course, but there's unlikely to be strong links."

Mayor Gail Sellers is unconcerned.

She says the mutant samples are several years old.

"Council does not consider the occurrence to be a problem," she said in a statement.

"Mutated cane toads in Gladstone are not a new phenomenon, nor is it an occurrence that is unique to the Gladstone region."