"It's a monster toad," said Paul Cowdy from FrogWatch which captured the cane toad Monday night.
"We've never seen a cane toad this big," he said on Tuesday. "It's a male and normally females are bigger."
The cane toad, regarded as a major pest in Australia, was one of 39 caught by a group from FrogWatch near Lee Point in Darwin. It measures 20.5 cm (8 inches) in length and weighs 840 grams (1.8 pounds) -- twice the normal weight.
Cane toads are one of Australia's worst environmental mistakes. The spread of the toads, whose skin is poisonous, has led to dramatic declines in populations of native snakes, goanna lizards and quolls, which are cat-sized marsupials.
"We capture them, put them in plastic bags, freeze them and turn them into liquid fertilizer," Cowdy said of the cane toads.
Cane toads were introduced from Hawaii in 1935 in a failed bid to control native cane beetles. There are now more than 200 million.