For nearly two weeks, locals have been on tenterhooks.
Could there really be a shark in Lake Alexander?
The popular suburban swimming area in Darwin's East Point has been closed to the public since a shark was reportedly sighted earlier this month.
"Until we know the answer, we won't be risking public safety," a City of Darwin spokesperson said at the time.
Word spread through the city, with locals wondering how a shark could have possibly ended up there.
Now, the Top End mystery has been solved, revealing the elusive intruder's true identity.
"They got a bit of a result last night, it wasn't a shark, but it was a result," Darwin council's parks and reserves manager Jamie Lewis said.
One-metre milkfish 'mistaken' for shark
NT Fisheries said the milkfish was more than one metre long, while the barramundi were 85 and 45 centimetres in length.
The theory is that the milkfish was actually seen two weeks ago with its fin precariously sticking out of the water, Mr Lewis said.
"A milkfish is a very large grey-coloured fish with very prominent vertical fins, it would be a very easy fish to mistake for a shark," he said.
Mr Lewis said council has spent about 50 hours line fishing the lake over the last two weeks to try catch it, and even had one of their lines broken.
He has a theory for that too.
"What we're thinking, maybe the barra's eaten the bait and broken the line off in an underwater snag."
While the believed culprit has been snagged, Mr Lewis said they still have not been able to 100 per cent confirm there wasn't shark.
"But we've been as diligent as possible and I think it's a safe assumption now that we're looking at milkfish", he said.
An unexpected catch that's hooked locals
The council is confident the case of the Lake Alexander shark sighting is now closed, and the lake was finally reopened.
As for how the fish got there in the first place, Mr Lewis believes they would have been put there.
"Our screens don't even let sand through in our pumping system," he said.
Mr Lewis said they very much preferred people did not place their fish in the lake in future.
"It's not ideal, it puts us in a bit of our position where we have to do something about it," he said.
NT Fisheries will conduct a final sweep of the lake on Thursday night.
