This poor Tuna was lured to its apparent demise by some idiot who decided to use a flash bolt at the aquarium. The poor fish, which is effectively out of shot at the beginning of the clip, comes speeding in at literal break neck velocity towards what it can only presumably think is a meal.

According to comments on the video, the speed at which Tuna can swim is limited by friction from the water burning their skin, which explains just how insanely fast this one appears to be going. However, like with a bird against a window, the poor fish is unable to recognize the obstacle of glass, and meets its demise. At least it was quick.

Presumably there were signs against flashes that were disobeyed, but really, does that person really think that a flash is going to help them get a better picture in that scenario? What do they think they're illuminating? That picture better be damn good, because it cost the life of a Tuna.