On 31 December 1788, Lieutenant Henry Lidgbird Ball of HMS Supply and Marine Lieutenant George Johnston ambushed two Aboriginal men at Kayeemy (Manly Cove). One escaped while the captured man, at first called Manly, was carried off to the settlement at Sydney Cove. He was detained in an attempt to learn something of the language and customs of the people, as well as information regarding natural resources. His name was found to be Arabanoo. This was rendered by the different writers at the time as Arooboonoo, Arooboonen, Araboonoo and Harrabanu. Although he had been captured in the territory of the Gamaragal, his clan is not known. Arabanoo remained in the settlement following the removal of his manacles.
He was present in the settlement during the outbreak of smallpox among the Aboriginal population in April 1789. Arabanoo helped to bury some of the victims and was present when two children, Nanbarry and Boorong (at first mistakenly called Abaroo) were brought into Sydney suffering from the disease.
Arabanoo contracted smallpox and died on 18 May 1789. He was buried in the governor's garden.