Too many people ignore the “no flash” sign when visiting places like museums, galleries, and in a recent case, a public aquarium. But the sign is there for a reason, and it was recently confirmed when the camera flashes confused a fish so much that it killed itself. The terrible event was captured on video, clearly showing the poor creature hurtling toward the light. Swimming at high speed, it hit the aquarium glass, and it sadly ended the fish’s life.

The video shared on Reddit shows a crowd at the aquarium and a variety of fish swimming in front of the spectators. You can see many visitors taking photos, and I counted nine flashes of light watching the 50-second clip. A tuna fish rushed into the glass, probably confusing the camera flashes for prey. It smashed against the aquarium wall, and it was dead on the spot. You can watch the video here, but keep in mind that it’s not for the faint-hearted.

“There’s a reason why most zoos and aquariums restrict flash photography,” one Redditor wrote, “because it disturbs and confuses the animals.” The “no flash” sign isn’t just to remind you that shooting with flash will give you awful glare and make your photos unusable. It’s there because you don’t have to make the poor fish kill themselves on top of being captivated. [via Digital Camera World]