Last Updated on: 31st October 2023, 10:54 pm
Fish navigate through the waters they live in, avoiding all manner of things that are in their way. However, without visible ears, can they hear sound?
Fish can hear sound, but their hearing is confined to low frequencies. Most fish can only hear between 800 to 1,000 Hz. A few can hear higher frequencies between 3,000 and 4,000 Hz.
As well as their internal ears, fish detect sound through their lateral line. Some fish also have a swim bladder that vibrates when it detects sound, sending messages to the brain.
As fish don’t have good hearing, their sound perception systems work with their internal ears to amplify the sounds they hear.
Fish detect sounds in many innovative ways, which keeps them alive.
How Do Fish Hear?
As mentioned, fish don’t have visible ears. However, in the ocean, sound travels around four times faster in water than in the air. This means hearing is vitally important for fish.
In particular, prey fish rely on their hearing to detect predators to escape. Hearing also tells fish more about their surroundings, including where food might be located.
Unfortunately, man-made sounds drown out the natural soundscape, making it difficult for fish to hear.
Not only does this hinder their ability to find mates and food, but it causes stress, which is harmful to fish. That’s why fish have adaptations alongside their ears that allow them to detect things around them.
In captivity, life is slightly different in that fish are less likely to encounter predators. However, they must still find food and move out of the way of the other fish in the tank, so their hearing is just as important.
Fish hear via the following bodily functions:
Fish have ear parts inside their head that allow them to pick up sounds. Fish’s bodies are the same density as water, so sound travels through them, so they don’t need outer ears like mammals.
The inner ear structures are called otoliths (ear stones), which act as a middle ear and comprise calcium carbonate and protein. The otoliths are denser than water and fish bodies, but their shape and size vary between species.
When sound passes through the fish, the otoliths wiggle around.
As the otoliths move, the difference in vibrations between them and the hair cells is detected by the auditory nerves. They’re then transmitted to the brain and translated into sound.
Most fish have a swim bladder inside their belly.
This balloon inflates when the fish wants to move up and deflates when they want to go down. However, it can also help fish hear as it acts like an eardrum and a secondary source of hearing.
When sound hits the air, it shakes the swim bladder, making it vibrate.
Fish can feel this deep inside their bellies. As described by PLOS One, the bladder’s size is thought to extend a fish’s frequency range up to 3 kHz.
Some fish also possess Weberian ossicles, which are a series of small bones that connect the swim bladder to their ears. Fish that have this can hear better than others.
Fish don’t just use their ears to hear. Integrative Zoology explains how all fish have a lateral line, which is a sensory system that runs down each side of the fish’s body.
They use it alongside their eyesight and ears to detect vibration, movement, and pressure changes. This enables them to “feel” when predators and dangers are nearby.
The lateral line is comprised of cilia. This is similar to the cilia that line the cochlea of the inner ears of terrestrial vertebrates. Each cilium is stimulated by water movement or pressure from a singular direction.
Do Fish Have Good Hearing?
Despite having internal ears, fish can’t hear very well. While they can hear sound due to vibrations in the inner ear, it’s a relatively basic system.
Most fish are split into two categories:
- Hearing generalists, which means that they can detect a limited range of frequencies.
- Hearing specialists, which means they can hear a broader range of frequencies.
Fish without swim bladders have inadequate hearing compared to fish that do and only hear an average of 400 Hz or less. Their hearing is also less sensitive. This includes some tuna fish, sharks, and rays.
The more closely the swim bladder and the ears are located to each other, the better the fish’s hearing. Fish with the best hearing have a swim bladder and a structure that connects them to the inner ear.
However, as described by The Journal of the Acoustical Society of America, the sounds that fishes hear are confined to low frequencies. While this is species-dependent, these frequencies are 800 to 1,000 Hz.
That being said, a small number of fish species can hear sounds between 3,000 to 4,000 Hz, according to a journal titled Fish Hearing and Sensitivity to Acoustic Impacts.
Fish with the worst hearing compensate in other ways by having better eyesight or a stronger lateral line than fish that can hear sounds well. These evolutionary adaptions are what kept them alive for so long.
Fish Hearing Frequency Range
As discussed, fish can hear varying levels of frequencies depending on their sensory organs. The following are the highest detected frequencies for a range of different fish species:
|Highest Hearing Frequency Detected (Hz)
Can Fish Hear You Talk?
Aquarium fish can hear human voices, but they can’t associate the sounds with words. Fish only hear these noises as chortles, bumps, pops, scrapes, and grunts; they can’t determine their meaning.
Some owners claim that their fish recognize their voices. However, this is unlikely.
When fish seemingly respond to human sounds, it’s probably because a loud, sudden sound has spooked them. It may even merely be a coincidence.
Similarly, owners commonly romanticize their fish’s reactions to sound as a signal that they recognize their voice. This is what they’re happy to believe, but it doesn’t make it real.
Fish aren’t usually bothered by sounds unless they’re directly affected by them. For example, if they hear sounds that signify a danger nearby or that food’s within the vicinity, they’ll react to it.
But because human voices outside their tank aren’t likely to cause strong enough vibrations, fish will ignore them. Higher-pitched voices with fewer vibrations are less likely to be heard than lower voices.
Also, tank filters can be loud. They also create vibrations that can manipulate sound waves, affecting how well fish hear. As explained by The International Journal of Animal Sound and its Recording, aquarium filters make a high amount of low-frequency sound, which can mask noises within the tank.
Instead of sound, fish are more likely to respond to visual cues. If you want to communicate with your fish, try using hand signals to see if your fish pays attention to them.
A study by the University of Oxford found that fish can distinguish between human faces by recognizing them. This means that your fish knows who you are, which can help you build a bond.
Can Fish Hear Music?
As mentioned, fish detect low-frequency sounds better because they travel faster and longer. This means fish can hear music with a low bass clearly, as they perceive them as vibrations.
Unfortunately, if you regularly play loud music with a significant amount of bass around your fish, you’re putting them under stress.
The fish may dart around the tank or head towards the bottom to protect themselves from what they think is dangerous.
Severe symptoms of music-related stress in fish include:
- Aggression (that can appear suddenly).
- Frantic swimming.
- “Surfing the glass,” where they swim up and down the sides of the tank.
- Loss of appetite.
- Change in physical appearance.
- Constant sickness.
- Excessive hiding.
While bass-heavy music can affect your fish, they’re unlikely to be troubled by normal music played at a reasonable level. Find a sound system that allows you to just the amount of bass and turn it right down.
Not only can fish hear music, but studies suggest they can distinguish between different songs.
A study described by Live Science discovered that goldfish could tell the difference between the works of Johann Sebastian Bach and Igor Stravinsky.
During their experiments, researchers played several songs from Bach and Stravinsky and trained goldfish to eat food from a ball when they played music from the former.
When researchers played Stravinsky’s work, the goldfish didn’t touch the food, suggesting they could tell the difference between the two musical pieces.
Even if you think your fish can’t hear your music, it’s not worth the risk of playing it too close to them.
Do Loud Noises Scare Fish?
Loud sounds scare fish, especially if they’re made underwater. The vibrations affect the fish, sending audible signals to their brain.
When a loud sound is made, fish swim to the bottom of the tank, pond, or lake to escape the “danger.” This is one of the primary reasons fishermen stay as still and quiet as possible when aiming to catch a fish.
If fish are close to a loud noise when it’s made, they could experience:
- Hearing loss.
- Tissue damage.
This is another reason why owners shouldn’t tap on glass fish aquariums. The knocking sends vibrations through the tank, scaring and disorienting the fish.
The noise will also sound much louder underwater, even if you think you’re tapping the tank gently.
Not only can loud noises damage the fish’s auditory organs, but it triggers them to swim away to find cover. While doing this, they could hurt their fins and tails on the tank’s decorative features.
While fish don’t hear specific sound frequencies, they hear enough to find food and keep themselves safe.
When keeping fish in an aquarium, try not to place loud music too close to them and keep them in a quiet, peaceful room away from too much noise.