When images of a "mutant" wolffish caught off the coast of Japan started making the rounds this week, panic ensued. But like a fictional "Godzilla", this fish is actually nothing to be worried about. 

Image: Hiroshi Hirasaka/Twitter

For starters, it's not as big as it looks. Remember last year's "giant" mantis shrimp? Just like in that photo, what you're seeing here is the result of forced perspective. By bringing the fish closer to the camera lens, fisherman Hiroshi Hirasaka is creating an optical illusion. This is the same reason trees appear to grow out of subjects' heads in family photos and Frodo Baggins looks so small in Peter Jackson's Lord of The Rings trilogy.

Image: Hiroshi Hirasaka/Twitter

As for the idea of giant, mutant Fukushima fish ... there is no scientific evidence to support claims that fallout from the Fukushima disaster has, or will, cause this to happen. Even right after the disaster, a swim in nearby waters would have dosed you with just 0.03% of the daily radiation an average Japanese resident receives. And much of that fallout has disappeared because of natural decomposition and decay.

Besides, even in the extremely unlikely event that radiation was the culprit here, we would actually expect to see smaller, not larger, fish. "Very, very few mutations lead to extra-large size," explains University of South Carolina radiation specialist Dr Timothy Mousseau. "[Instead], they grow less efficiently, they're less capable of catching food and they tend to not live as long. 

All that said, this catch is still an impressive one. Wolffish (family Anarhichadidae) average about three feet in length (110 cm), but can get bigger. What Hirasaka has landed is a very old and very healthy specimen. "If you look hard and long enough there's always a few that manage to survive long enough to achieve these large sizes," says Mousseau.

Image: Hiroshi Hirasaka/Twitter
Image: Hiroshi Hirasaka/Twitter
Image: Hiroshi Hirasaka/Twitter
wolffish 6-2015-9-17
Image: Hiroshi Hirasaka/Twitter
wolffish 7-2015-9-17
Another wolffish caught by Hirasaka shows average size. Image: Hiroshi Hirasaka/Twitter

Top header image: Asenath Waite/Flickr