An archerfish presses its tongue into a groove on the roof of its mouth to form a narrow tube, then snaps its gill covers shut to force water through it. Rather than leaving the mouth at one steady speed, the fish varies its own mouth-closing speed during the shot so that water released later travels faster than water released first, causing the trailing water to catch up and pile into a single fast-moving blob just before impact.
Recorded shots can reach targets over a metre away, with the final water mass hitting insects with more momentum than the initial ejection speed alone would predict. Juveniles are noticeably less accurate than adults and improve with repeated attempts, suggesting the skill is refined through practice rather than fixed from birth.
A common misconception is that archerfish simply spit water like a squirt gun; the acceleration of the jet after leaving the mouth is a hydrodynamic effect the fish actively shapes, not incidental. Researchers still debate exactly how much of the aiming, including compensation for the refraction of light at the water's surface, relies on learned visual calculation versus simpler reflexive adjustments.