Examination of the fish, including analysing its otoliths (ear bones), by DPI and other experts at the Australian Museum and Fish Ageing Laboratory at the Sydney Institute of Marine Science have revealed the sea bass was six years of age and was a female.

Measuring 113cm and weighing 12.53kg (27.63lb) the fish is more than twice the weight and length of sea bass of a similar age studied by fisheries scientists in their home waters of the Western Pacific.

In fact, Hall's sea bass has been described by DPI experts as being "exceptional in both size and growth rates". As it turns out, it is only just off the IGFA All Tackle record, a fish which weighed in at 28lb 15oz.

Japanese sea bass - known as "suzuki" in Japan - are protandrous hermaphrodites, reaching sexual maturity as males at about two years of age and then changing into females as they become older.

Hall caught his sea bass early in the morning on February 13 of this year while targeting mulloway on fly in the Hunter River at Newcastle.

He initially tagged and tried to release it. Discovering it was unsuitable for release, he kept it and put up a post on his Facebook page.

Not surprisingly, the fish created something of a social media storm. It also attracted considerable interest in the scientific community, with the upshot being that Hall very kindly agreed to donate the frame to the Australian Museum and DPI for analysis and study.

Prior to that, Hall arranged for the fish to be taxidermied and it now holds pride of place on the wall at his home.

DPI understands that small numbers of Japanese sea bass have previously been recorded in Sydney Harbour, with speculation that they may have been transported as fry or larvae in ship ballast water.

At this stage, it is uncertain how the fish Ben caught ended up in the Hunter River.