A Darwin-based crocodile expert says farming of the reptiles is not cruel and has described a report by the World Animal Protection group as misguided.

The report said crocodile farms were inhumane, unclean and overcrowded, leading to stressed and aggressive animals that fight each other.

"Because of competition for limited space in the pits the crocodiles will fight each other, sometimes to the death," the report stated.

"They also rip off one another's legs and such serious injuries can eventually kill them too."

Director of Darwin's Crocodylus Park Professor Grahame Webb has worked with the reptiles for more than 40 years and has been actively involved in conservation and management of saltwater crocodiles.

"Just about every croc [in the wild] over three metres is scarred, has legs missing, has a tail amputated, snout amputated, those things don't really occur in the farming sector," he said.

Professor Webb said life in the wild was tough and the animals kept in farms enjoyed a better life in captivity.

"If you're farming crocodiles for the high-end market one scratch, one bite mark reduces its value by 50 per cent," he said.

He said the financial incentive meant crocodile farm owners went to great lengths to keep the animals in good condition, something that did not happen in the wild.