Beneath the surface of busy reef waters, a quieter catastrophe unfolds: the noise of passing motorboats does not simply disturb reef fish — it reshapes them. Research from universities in the UK and Australia reveals that spiny chromis exposed to boat noise during embryonic and juvenile development grow smaller and lose the instinctive ability to flee predators, even after the noise is long gone. The findings arrive as coral reefs already bear the weight of warming seas and human pressure, adding sound itself to the list of invisible threats that erode life at its most foundational stage.