Barracuda

A barracuda is a ray finned-fish that is about 6 feet in length. It is found in tropical and subtropical oceans worldwide. It is of the genus Sphyraena, the only genus in the family Sphyraenidae. Infamous for its intimidating and ferocious behavior, it is the reason that divers take off any shiny or glittery bracelets in the water. They eat fish that are silver in color, which may cause them to attack someone if they are wearing any shimmering objects. 
These fish usually stay near the top of the water around sea grass and coral reefs.