The ocean is noisier than one might think.
By rapidly vibrating their internal air sacs, rubbing teeth and fin spines together — and, yes, even farting — fish emit a surprising variety of low-frequency grunts, boops, clicks, hums, and bubbling burps.
And now scientists are finally learning how to decode them.
With the help of Aalto University and the Cornell Lab of Ornithology’s K. Lisa Yang Center for Conservation Bioacoustics, scientists at FishEye Collaborative have developed a new tool that combines underwater sound recording and 360-degree video to match sounds to the fish emitting them with pinpoint precision.
“Spatial Audio lets you hear the direction from which sounds arrive at the camera,” said Marc Dantzker, FishEye Collaborative’s executive director, after his research was published in “Methods in Ecology and Evolution.”
“When we visualize that sound and lay the picture on top of the 360° image, the result is a video that can reveal which sound came from which fish,” Dantzker explained.
However, the idea of creating an underwater library of fish sounds, filtered by species, is a daunting task — even with the nonprofit’s burgeoning technology.
“When it comes to identifying sounds, the same biodiversity we aim to protect is also our greatest challenge,” Marc Dantzker said.
“The diversity of fish sounds on a coral reef rivals that of birds in a rainforest. In the Caribbean alone, we estimate that over 700 fish species produce sounds.”
According to Cornell, the new technology works similarly to smartphone apps like the Cornell Lab of Ornithology’s Merlin Bird ID, which uses the world’s largest database of birds to identify species by song and sound.
“We are a long way from being able to build ‘Merlin’ for the oceans, but the sounds are useful for scientists and conservationists right away,” said Aaron Rice, a principal ecologist at the Cornell Lab who also served as a senior author of the study.
Still, it’s a start.
“By discovering the identity of these hidden voices, acoustics will become a powerful indicator of reef health and resilience — and a strategy to monitor wider and deeper,” said study co-author Matt Duggan.
Unlike other underwater tools, which often require divers and research teams to help facilitate their use, the researchers also said it had added value as technology that can be left underwater for prolonged amounts of time.
It also means discovering species behaviors that are entirely new to science. So far, the nonprofit has accurately detected 46 species of fish through their passive acoustic monitoring technology — and half of them were not known to emit sound at all.
“The fact that our recording system is put out in nature and can record for long periods of time means that we’re able to capture species’ behaviors and sounds that have never before been witnessed,” Rice said.
In 2026, the FishEye Collaborative hopes to expand beyond the Caribbean to reefs in Hawaii and Indonesia.
“By identifying which species make which sounds,” Dantzker said, “we’re making it possible to decode reef soundscapes, transforming acoustic monitoring into a powerful tool for ocean conservation.”
To see — and hear — the colorful variety of fish that have been catalogued so far, visit the FishEye Collaborative Fish Sound Library.
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Header image via FishEyeCollaborative / Symeon Manias
