Aurora skipper Ant Smith had hoped to be allowed to keep the projectile he pulled up in a net of tarakihi 5km off Cape Saunders on Monday.
"It would be the strangest thing I've dredged up in 23 years of fishing," he said yesterday.
"I wanted to find out if it was safe or not. If it was, then I had a space all set out in my garden for it."
However, the New Zealand Army, in response to an approach from the Otago Daily Times, said Mr Smith could not keep the device.
"The item picked up was a 25lb [11kg] practice aircraft bomb," Lieutenant Andrew Ranger, of the Southern Explosive Ordnance Disposal (EOD) Troop, said yesterday.
"Although a practice bomb, they could still be fitted with a spotting charge, which is designed to function when the bomb hits the ground, and emit a bright flash and cloud of smoke. Therefore, a live one of these is still potentially harmful."
The bomb had been removed in a high-tech, bomb-proof blanket and destroyed after it was confirmed the spotting charge in the bomb was no longer present, Lt Ranger said.
"All items that we recover during EOD callouts are removed and destroyed."
Careys Bay was cordoned off and traffic diverted from 10am to 4pm on Tuesday while the bomb squad travelled from Christchurch to deal with the device.
