Unsettling moment massive fish 'kills itself' after being startled by camera flash in aquarium

A visitor to an aquarium caught the horrific moment a fish ‘killed itself’ after being startled by the flash of a camera.

In the clip, which is believed to have been filmed back in 2013, a group of people can be seen gathered around a huge tank in an aquarium in Japan.

While some folks are happy enough to just look at the fish swimming around, some pull out their cameras to get a snap of the creatures, with flashes from their devices clearly visible in the footage.

However, as the light from flashes intensifies it appears to have a particularly adverse effect on one large tuna, which reacts to the flashing by ramming itself into the glass - something some social media users say was a deliberate attempt to hurt itself.

Sadly, the agitated sea creature knocked itself out and reportedly died.

Reddit/u/29PiecesOfSilver

Aquarium tanks are usually made out of a highly reflective acrylic material and can negatively affect the vision of the fish on the other side of the glass.

"This is why flash photography should not allowed in aquariums," a Reddit user who posted the clip thought.

"The fish cannot see the glass and think the water continues onward in that direction as the flashes resemble reflective light bouncing off the water."

Viewers were shocked by the footage, with one person commenting: "Every adult has walked into a glass or mesh-screen door at maybe a couple of miles per hour.

"Now, imagine the speed at which that fish swam into the aquarium's dense glass-wall. That is horrific."

Another added: "Wow I'd never seen tuna swim and didn't know they could be that fast. That almost looked unreal."

Reddit/u/29PiecesOfSilver

Someone else wrote: "I think the camera flashes confused it into a feeding response and that caused it to blindly ram into the glass.

"There's a reason why most zoos and aquariums restrict flash photography because it disturbs and confuses the animals."

According to the WWF, some species of tuna are considered to be 'the Ferraris of the ocean' and can swim up to 43 miles per hour.

Despite being able to move so quickly through the water, the Atlantic bluefin, for example, can reach ten feet in length and weigh as much as 2000 pounds (more than a horse).

It's their unique body shape and strong fins which give them 'special swimming muscles' to cruise through the ocean with great speed.