If you’ve ever thought that your goldfish can’t hear or won’t respond to the music that you blast in your room, it’s time to think again. Though few people know this, all fish respond to sound, and several recent studies have shown that fish can even tell the difference between genres of music and composers.
Goldfish Successfully Identify Bach
In a recent experiment, scientists trained goldfish to eat from a food ball while the classical music of Bach played in the background. Later, they switched Bach out for the more modern Stravinsky, and the goldfish didn’t touch their food ball. This suggests that they could tell the difference between the music of the two composers and had come to associate Bach with the reward they got from the food ball.
How Fish Hear
Some people may believe that fish cannot hear because they don’t have ears, but fish actually have several different sound perception organs. Different species of fish can hear using cilia (fine nerve hairs), bladders, otoliths, accelerometers or some combination of those organs. The cilia that line the sides of some fish are actually very similar to the cilia that line the cochlea in the inner ear of humans and other land-dwelling vertebrates.
How Sound Travels in Water
Another misconception that some people have is that sound does not travel very well in water. If you’ve ever stuck your head under water and had someone call out to you, you know that water muffles sound. However, sound waves travel in water much the same way they travel in the air. The only reason we perceive sound as being muffled under water is because water is denser than air, and this density of the medium reduces the intensity of the sound. However, because fish have sound perception organs specifically adapted for under-water hearing, they do not have the same trouble hearing under water as humans do.
Why Fish Might Respond to Music
Fish need to be able to hear under water for their own survival. Most fish can only see close distances because their vision is limited by the distance of light rays under water. Therefore, being able to hear may help them avoid danger before predators swim too close. In the experiment outlined above, the goldfish were conditioned behaviorally to identify Bach because they were rewarded when this music played. Both humans and animals will adopt certain behaviors when they come to associate them with rewards. Therefore, a fish’s ability to differentiate between sounds allows it to both survive and receive positive reinforcement.