The ocean isn't silent—it's a cacophony of grunts, growls, knocks, and even airplane-loud booms. Nearly 1,000 fish species worldwide produce sounds, and scientists have recently cracked the code on identifying them by their unique "voices." In 2025, researchers at the University of Victoria developed AI that can distinguish between eight different fish species based solely on their acoustic signatures, achieving up to 88% accuracy.

Quillback Rockfish make rapid defensive grunts when chased. Copper Rockfish emit repeated knocking sounds while hunting prey. Black Rockfish produce long, frog-like croaks. Each species has evolved distinct vocalizations for different situations—essentially, underwater dialects.

The Loudest Fish on Earth

Not all fish whisper. The Danionella cerebrum, a transparent fish barely half an inch long, can blast sounds exceeding 140 decibels—louder than a jet engine at close range. Meanwhile, male plainfin midshipman fish, nicknamed "California singing fish," hum continuously during mating season by vibrating their swim bladders with specialized sonic muscles. Coastal residents have reported the droning noise keeping them awake at night.

How Fish Make Sounds Without Vocal Cords

Fish have evolved three primary methods of sound production:

Drumming: Sonic muscles vibrate against the gas-filled swim bladder like a biological drum
Stridulation: Rubbing or striking skeletal components together (think grinding teeth or clicking bones)
Hydrodynamics: Rapid changes in swimming speed and direction create audible pulses

The drums and croakers family (Sciaenidae) are masters of the first technique, possessing specialized muscles that literally drum their swim bladders to produce low-frequency calls.

Sound travels five times faster underwater than in air—about 1,500 meters per second—making acoustic communication far more effective than visual signals in murky or deep waters. Fish use these vocalizations to attract mates, warn rivals, coordinate group movements, and even mob predators through collective acoustic displays.

The Evolutionary Timeline

Fish didn't just start chatting recently. Research suggests acoustic communication in fish dates back at least 155 million years, meaning dinosaurs shared the planet with gossipy fish. Today, sound-producing species appear in 133 of the 549 known fish families, spanning marine, freshwater, and brackish environments across nearly every region on Earth.

But underwater conversation comes with risks. Bottlenose dolphins hunt by eavesdropping on fish sounds—up to 80% of their diet consists of vocal fish species. It's the aquatic equivalent of being overheard by your predator. Increasingly, human-generated noise from vessels is forcing fish to speak louder (the Lombard effect) or change their calling patterns entirely, disrupting millions of years of finely-tuned communication.

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