The man who originally named Gus, the beloved Australian blue groper, says claims he has died at the hands of a Kiwi spearfisherman are untrue. 

A 26-year-old man from New Zealand was fined A$500 after illegally spearing a blue groper at a marine reserve in Sydney on December 30. 

Photos shared widely on social media show the wet-suited man triumphantly holding the slain groper after spearing him at Oak Park Beach. 

There was an outpouring of grief and anger from locals with the slaughtered fish widely believed to be 40-year-old Gus, who lived on a local reef and was particularly friendly to divers. 

A 26-year-old Kiwi has been fined $500 for killing a protected groper called Gus in a Sydney marine reserve. Photo / Supplied 

But wildlife documentary maker David Ireland has told the Daily Mail Australia the dead fish is not, in fact, Gus. 

Ireland said Gus was bigger than the fish shown in photos, and also had a distinctive scar on his tail from a previous spearfishing encounter. 

The 76-year-old ran a nearby dive shop and befriended the fish in the 1980s when he was teaching diving. He said Gus was able to instantly pick him out from other divers. 

Wildlife documentary maker David Ireland claims Sydney's blue groper Gus - pictured in happier times - is likely still alive. Photo / Abyss Scuba Diving 

“Eventually he was so tame, I could put my arms around him like a puppy dog and pat him ... I named him Gus, and that went on for decades,” Ireland told the news outlet. 

• Locals devastated after Kiwi 'triumphantly' spears iconic Sydney fish

“I knew him very well - and the fish that was killed by that idiot was not Gus.” 

A 26-year-old Kiwi has been fined $500 for killing a protected groper called Gus in a Sydney marine reserve. Photo / Supplied 

There were 7-10 groper living in the area and the dead fish was likely to be one of Gus’ offspring, Ireland said. 

He had choice words for the spearfisherman - saying there were “always f***wits everywhere” and the man’s wetsuit and gear showed he knew what he was doing - and must have known it was illegal. 

A 26-year-old Kiwi has been fined $500 for killing a protected groper called Gus in a Sydney marine reserve. Photo / Supplied 

But there would have been no sport in the kill as blue groper were so friendly that the fish had likely swum right up to the man. 

“It was me who tamed Gus. It was me who named Gus. You’ve got all these so-called experts coming out of the woodwork - they know nothing.” 

The blue groper is the New South Wales’ official fish and spearfishing the species is prohibited. The maximum fine is $22,000 or six months in prison. 

State police said the man had been questioned and fined $A500 for fishing in a no-fishing zone. 

He was also reportedly fined another A$300 by the Department of Primary Industries, which told another news service the man showed “significant remorse” when he was confronted by fishery officers. 

Police said the dead fish could not be found and was thought to have been returned to the sea.