The transparent fish Danionella cerebrum, which is only 12 mm in size, can make noises up to 140 dB, which is the same volume as someone standing 100 meters away from a passenger jet during takeoff.

Although Danionella cerebrum fish were first detected in the 1980s, it wasn't until 2021 that the species was formally classified due to the discovery of minute morphological distinctions between it and Danionella translucida.

The two species are so similar to one another and so little, roughly the size of a human fingernail, that it would need a microscope to distinguish the differences between them.

Furthermore, a group of scientists recently found a further intriguing characteristic of Danionella cerebrum that not only distinguishes it from its species sibling but also places it at the top of the list of the world's loudest animals.

The small transparent fish can make noises as loud as a gunshot by combining its sonic muscles and drumming cartilage.

Dr Ralf Britz, an ichthyologist at the Senckenberg Natural History Collections, stated, "This tiny fish can produce sounds of over 140 dB at a distance of 10 to 12 mm— this is comparable to the noise a human perceives of an aeroplane during take-off at a distance of 100 m and quite unusual for an animal of such diminutive size."

There are louder animals in the world, such as the pistol shrimp, which may produce sounds as loud as 250 decibels, but fishes are normally among the quietest creatures on the planet, so it’s remarkable to discover one as loud as an ambulance siren or a jackhammer, especially one this small. But the technique Danionella cerebrum utilizes to make the deafening sound is even more remarkable.

High-speed video recordings showed that a rib near the fish's swim bladder is moved onto a piece of drumming cartilage by a unique fatigue-resistant muscle to make loud noises.

This equipment accelerates the drumming cartilage with a force of approximately 2,000g and shoots it against the swim bladder to produce a quick, loud pulse,” Dr. Britz explained. “These pulses are strung together to produce calls with either bilaterally alternating or unilateral muscle contractions.”

Interestingly, the rib is much harder in males, which is most likely why the female Danionella cerebrum does not produce the same loud sounds.

As for the function of the sounds, scientists have yet to uncover it, but they say that it could help the fish navigate murky waters or it could be an aggressive approach employed by males to warn off competition during mating.