The largest species of crocodile is the Saltwater Crocodile and one of the biggest specimens was Gomek (on the photo), measured 5.5 m (17.9 feet) and weighed well over 2,000 pounds (roughly 900 kg) when he died in February 1997. Gomek was captured by George Craig in Papua New Guinea and sold to St. Augustine Alligator Farm in Florida. George also captured even larger crocodile, Oscar, who currently lives on Green Island in Queensland.
Gomek feeding on the famous video record.
In other web-sites we can find that the two largest crocodiles in captivity are Cassius at Marineland Melanesia on Green Island, Australia and Chai Yai (probably on the picture with Steve Irwin), a saltwater/siamese hybrid.
Cassius is 18 feet (5.5m) long. Yai is listed by the Guinness Book of Records at being 19 feet 8 inches (6 m).
Sources: Crocodilian Biology Database, crocodilian.com