Fish can hear, and sound provides information over greater distances than any other sense, especially in dark or turbid water. Sound propagates rapidly through water, making hearing vital for survival, orientation, and communication. However, the idea of a fish “hearing music” as humans do is misleading, because their auditory experience is fundamentally different.
The Fish Auditory System
Fish possess a sophisticated auditory system capable of detecting two physical components of sound: the pressure wave and the particle motion. The primary hearing organs are the inner ears, which are located inside the skull and lack the visible outer ear structure of terrestrial vertebrates. The inner ear contains dense, calcium carbonate structures called otoliths, or “ear stones,” which are suspended near sensory hair cells. When a sound wave passes through the water, the fish’s body moves along with the wave due to its density being similar to water. The much denser otoliths lag behind this movement, causing them to shear against the sensory hair cells, which generates the neural signal that the brain interprets as sound.
For many species, the swim bladder, a gas-filled organ used primarily for buoyancy control, plays a role in amplifying the sound. Because gas is highly compressible, the pressure component of a sound wave causes the swim bladder to vibrate significantly. In some fish, like minnows and catfish, a series of bones called Weberian ossicles mechanically link the vibrating swim bladder to the inner ear, dramatically increasing hearing sensitivity.
A secondary sensory system, the lateral line, runs along the sides of the fish and detects nearby low-frequency water movements and vibrations. Its function is distinct from the inner ear, typically effective only over a short range (about one to two body lengths).
Hearing Range and Sound Perception
Fish hearing is generally biased toward much lower frequencies than human hearing, with most species detecting sounds in the range of 40 to 1,000 Hertz (Hz). This low-frequency bias means that many of the higher-pitched notes and complex harmonics that define human music are likely imperceptible to most fish. For comparison, a human teenager can typically hear sounds up to 20,000 Hz.
Species with special anatomical adaptations, such as the Weberian ossicles, are known as “hearing specialists” and can detect frequencies up to 5,000 Hz. A few notable exceptions, such as the American shad, can even detect ultrasonic frequencies above 180,000 Hz. This is thought to be an evolutionary adaptation to detect the echolocation signals of dolphins.
Because fish hearing relies on detecting particle motion and vibration, they perceive individual frequencies and intense vibrations. However, they lack the complex cortical processing structures necessary to appreciate the abstract qualities of music, such as melody, pitch, and rhythm.
How Fish React to Underwater Noise
Sound is important for fish survival, used to locate mates, detect predators, find food, and navigate. Many species communicate using sound, producing calls by grinding teeth or using specialized muscles to “drum” against the swim bladder, often related to courtship or territorial defense.
The increasing presence of human-made, or anthropogenic, noise in aquatic environments has become a source of significant disruption to these natural behaviors. Continuous sounds from shipping or dredging can mask the biologically relevant sounds fish need to detect. This interference affects their communication and ability to hear threats.
Louder, impulsive noises, such as those from pile driving or seismic surveys, can trigger alarm responses, causing fish to flee an area or alter their migratory paths. This noise pollution can lead to chronic stress, measurable by elevated stress hormones, and can disrupt feeding patterns and reproductive success. In extreme cases, intense sounds can cause physical damage, including temporary or permanent hearing loss.