Two brothers were fishing off Wolfe Island near Kingston, Ontario, earlier this month when they spotted a shark.

Or did they?

In a video posted last week, the brothers appear to be reeling in a fish when a dorsal-finned shark surfaces — according to the video uploader, it snatched the catch off the hook — then disappears under the water.

The shark in the video is believed to be a bull shark, "an aggressive carnivore not adverse to freshwater and known to travel inland," the National Post reported.

The video went viral, with some locals now concerned for their safety in the water.

"I think a lot of people aren’t sure if it's a true story or not," Erin Whalen, a waitress at a restaurant on Wolfe Island, said. "But it's got a lot of parents being wary."

Others, however, aren't convinced.

"You're pulling my leg, of course," Wolfe Island Mayor Denis Doyle told the National Post when contacted by phone on Tuesday.

"That's a good one," he said, joking that it would be more likely to find "sharks on Bay Street" in Toronto. "It sounds like a Loch Ness monster."

Doyle watched the video and admitted that it could have been shot in his area, but he couldn’t be certain.

Wynfield Woodman, who ran fishing tours in the area for 40 years, believes the sighting was likely a sturgeon.

Other viewers are adamant that the "shark" is a catfish.

"There's no way it's a shark. It's a catfish," wrote Kristen Lamarche. "The dorsal fin is too close to the head to be a shark, and the shark's backs don't have a pointy ridge like this one."

And a spokesperson for the Ontario Ministry of Natural Resources said there isn't enough "good solid physical evidence" to confirm what it is.

"Not like anyone has ever posted a 'Fake Video' on the internet before… right?" wrote Variety 104.5's Nathan Carr.

What do you think, real shark, real something-else, or just another Internet hoax?

Here's another shark image that's getting some serious attention. Brazailian underwater photographer Adriana Basques captured a 26-foot-long whale shark, with its 4-foot-wide mouth open, seemingly ready to chow down on a boat full of fisherman. (In reality, the whale shark was touching the dome of the photographer's camera.)

"It might look scary when you see one with a huge open mouth coming in your direction," Basques told Caters News Agency. "But they usually have a very good sense of space and will turn before they get too close, although this is not what happened with the particular one in this image."

The optical-illusion photo is up for the People's Choice Award in the Wildlife Photographer of the Year competition held by the Natural History Museum in London.