There's a fish smaller than a dime that makes really loud sounds

A MARTÍNEZ, HOST:

There's a fish smaller than a dime that makes really loud sounds, big time.

(SOUNDBITE OF FISH CREAKING)

STEVE INSKEEP, HOST:

That's the tiny fish called the Danionella cerebrum, found in streams in Myanmar. It can make sounds that exceed 140 decibels, which is as loud as fireworks or a jet engine.

VERITY COOK: It's the smallest animal I came across that makes the sound this loud.

MARTÍNEZ: Although you have to be very close to hear it. Verity Cook is the lead author of a study of the fish, and she says the 140-decibel sounds do not carry like a jet engine.

COOK: This is when you're one fish length away. Like, the other fish, when they're close to the fish, this is what they hear.

INSKEEP: It's a steady sound.

COOK: It's more like walking through, like, a field of insects. You hear the sound very clearly. But, yeah, it doesn't wake you up.

INSKEEP: So how do the fish make this noise? They are transparent, which made it easier to see. Cook says the muscles of their swim bladders, which control their movements in the water, build tension and then release.

COOK: This is like hitting a drum very quickly. And this is what creates the sound. And then the left and right muscles alternate very fast, 120 hertz. And then this is what you hear, this buzzing sound.

MARTÍNEZ: And only the male fish make this noise, and only when they're around other fish.

COOK: So we're quite sure that it's some sort of communication signal that they have. At the moment, speculation is that they either make sounds for aggressive encounters when they're with other males or for, like, courtship and, like, mating behavior.

INSKEEP: So the noise of the loudest fish may be the sound of desire.

(SOUNDBITE OF MUSIC) Transcript provided by NPR, Copyright NPR.