Archerfish, water pistol.

Archerfish use their mouths as squirt guns to shoot down their prey. The high-powered streams of water they can spit out (up to 5 meters long) are so deadly that insects even 10 feet away are killed instantly and knocked into the water in just one-tenth of a second.

Image source awsomeocean

It is the accuracy with which archer fish shoot deadly darts of water at prey that earned the species its name.

The jets of water are produced when archer fish press their tongues against a groove in their mouths to form a gun-barrel-like shape, and close their gills to force out a spurt of water.