Needlefish are not dangerous because they are aggressive, venomous or poisonous, or pack a mean bite. They're dangerous mostly because of their shape, their needle-like teeth, and their ability to become airborne. The dagger-shaped fish usually swim just a few inches below the water's surface, but they can launch themselves out of the water at speeds of up to 37 miles per hour. They have been known to cause injury and sometimes death in people who happen to be in their way.