An Australian crocodile called Cassius Clay was on Thursday declared the biggest in captivity by Guinness World Records, although his reign may be brief after reports of a rival giant emerged. Measuring just under 5.5 metres (18 feet) and weighing close to a tonne, Cassius was captured in the Northern Territory in 1984. Named after the legendary boxer, better known as Muhammad Ali, he has called the Marineland Melanesia crocodile park on Green Island, off the far north Queensland coast, home for the past 24 years. Guinness World Records spokesman Chris Sheedy said Cassius was one of a few record holders to be honoured with a double-page spread in the 2012 Book of Records. "We thought this record was so amazing that it deserved its own two-page spread and that's now going out in four million copies worldwide," he told Australian Associated Press. However, Sheedy said the crocodile's record may be brief after reports earlier this month of a monster 6.4-metre beast that was trapped in the southern Philippines. That crocodile is suspected of eating a farmer who went missing in July and of killing a 12-year-old girl whose head was bitten off. "Until it's in acceptable captivity, which is humane and professional, and until it has been properly measured, we can't accept it," said Sheedy.