The Mysterious World of Fish Communication/ "The Oceans Are Full of Sound"

From mysterious clicking noises in a laboratory aquarium to frogfish hums and songs, scientists are discovering the wonder of underwater communication, the BBC reports.

When you think of how fish communicate with each other, you might imagine little more than an aquatic silence punctuated by the odd bubble.

In reality, however, "the oceans are full of sounds," says a researcher at Cornell University in Ithaca, New York. Clicks, grunts, plops and screams are just some of the sounds that fish use to signal to those around them underwater. Some, such as frogfish, sing beautiful songs to each other, and others, such as herrings, communicate using their digestive tracts – more on this later. They use these signals for various reasons: to warn competitors, to raise an alarm, and even to win over their potential mates.

Clues that fish are more talkative than we thought they were have been a
round since the 4th century, from the works of Aristotle to the whispers of traditional fishing communities. But our ability to listen to the fish was limited by the devices used for underwater recording

Acoustic monitoring has come a long way since the 1930s, and scientists now use underwater microphones, called hydrophones, to listen to marine life. Technology invented during World War II to search for submarines has helped us listen to how fish talk to each other in the depths of oceans, rivers and lakes.

Of the approximately 34,000-35,000 species of ray-finned fish, which include cod, tuna, trout and salmon, about 4% have been studied for sound production. But Rice's research suggests we've only scratched the surface of the mysterious world of fish communication. According to him, up to two-thirds of fish could make underwater noises.

In February 2024, researchers in Germany discovered a small, transparent fish called Danionella cerebrum that produces a sound so loud it could rival a pneumatic drill.

They discovered it after hearing mysterious clicking noises coming from fish tanks in their laboratory.

Fish tend to get agitated for reproductive and territorial reasons. Or, more simply, for food and sex. Underwater sounds sound much clearer to fish than to us.

According to ecologists at the University of Florida who study fish bioacoustics, "Underwater sound travels five times faster than in air." "If we put our heads in a pool and try to figure out where a sound is coming from, we have a very hard time doing it. Fish, on the other hand, can gather directional information from underwater sounds."

The researchers compiled more than 1,200 such noises in an online library called FishSounds. Among all the grunts, chirps and squeaks, some sounds – and the behaviors they signal – stand out