Male Danionella cerebrum fish are only about the size of a fingernail, but can produce noises exceeding 140 decibels, according to research published in the journal PNAS.
This sound intensity is equivalent to fireworks exploding, a rifle shot, a jackhammer or an ambulance siren and is even louder than an airplane taking off (130 decibels).

The Danionella cerebrum is one of the smallest fish in the world, reaching a maximum size of 12 mm for adults. It also has the smallest known brain of any vertebrate.
Only male fish make such loud sounds, female fish do not.
To produce such a loud sound, the tiny fish uses the elasticity of its cartilage to impact its swim bladder, a gas-filled organ that controls the fish’s buoyancy. However, the swim bladder mechanism is not a plausible explanation for the source of the sound, so the exact mechanism that produces such a loud sound remains a mystery.
According to scientists, this small fish makes such loud sounds to create waves, helping the fish move better in murky water and is also a tactic used by males to protect their territory or compete for prey with other individuals.