At first glance, fish don't appear to have ears, but that doesn't mean they can't hear. While there are usually no openings on a fish's head for sound to enter, they do have inner ears that pick-up sound through their body.
Yes, fish can hear you talk!
Sounds that are created above water typically do not carry enough force to penetrate the surface tension of the water, so talking on the boat or loud noise may not affect fish as much as your fellow anglers may want you to think. Your voice is unlikely to spook or scare fish away.
Although the sounds that fishes hear are confined to low frequencies (often to no more than 800–1000 Hz, but this is very species dependent) in comparison with many terrestrial vertebrates and aquatic mammals, fishes are able to discriminate between sounds of different amplitude and frequency, and between calls that ...
Fish is extremely sensitive to low-frequency vibrations, below some 10s of Herz. If the sound source is sufficiently intense, fish usually respond by swimming away from the source. The reason for this is probably that low frequency sounds usually indicates an approaching predator.
Unlike us humans, fish hear using an inner ear located inside the brain cavity, just behind the eyes. There's no need for an outer ear, as the fish's body is about the same density as the water, and so sounds travel through the water, the fish, to its ear.
Fish have gills that allow them to “breathe” oxygen dissolved in the water. Water enters the mouth, passes over the gills, and exits the body through a special opening. This keeps an adequate amount of water in their bodies and they don't feel thirsty.
Yes, fish experience both physical and emotional pain. Scientists say that it's likely a different type than what humans experience, but it's pain nonetheless. Fish have nerve cell endings called nociceptors, which alert their bodies to potential harm such as high temperatures, intense pressure, and harmful chemicals.
Besides being able to see their prey and recognize their owners, fish also can see a range of colors, since they have color receptors in their eyes. Many species of fish can also see ultraviolet light, which humans can't.
The answer is yes! They can. Although their hearing apparatus may work rather differently from our own, wild and aquarium fish tend to be very good at hearing sounds.
Researchers from Keio University in Japan have studied the effects of playing music for fish kept in indoor glass tanks and outdoor koi ponds, and one of the conclusions was that fish can not only hear music but also react to harmonious sounds.
Neurobiologists have long recognized that fish have nervous systems that comprehend and respond to pain. Fish, like “higher vertebrates,” have neurotransmitters such as endorphins that relieve suffering—the only reason for their nervous systems to produce these painkillers is to alleviate pain.
While fish do not sleep in the same way that land mammals sleep, most fish do rest. Research shows that fish may reduce their activity and metabolism while remaining alert to danger. Some fish float in place, some wedge themselves into a secure spot in the mud or coral, and some even locate a suitable nest.
When exposed to increased amounts of noise for longer periods, fish can experience stress, loss of hearing and various changes to their behaviors, explains a team of researchers at Cardiff University in the United Kingdom who examined the effects of noise pollution on fish.
The specialised retinas of some nocturnal coral fish result in faster vision and greater sensitivity to dim and bright light. The same adaptation may enable deep-sea animals to see in darkness.
Fish can recognise members of the same species and tell if other fish are siblings, but they probably can't identify themselves. Fish can't see themselves, and so presumably don't know what they look like. But they're still able to recognise other members of their own species and join them in a shoal.
There has recently been increasing evidence demonstrating that fish can discriminate between familiar individuals based on facial characteristics (i.e., true individual recognition) and can even identify individual humans faces (e.g., refs. 22–29).
Nerves, brain structure, brain chemistry and behaviour – all evidence indicates that, to varying degrees, fish can feel pain, fear and psychological stress.
Luckily for this aspect, most fish used for residential aquariums are reef fish that live in the safety of the somewhat small and tight areas of the reef. So yes, fish do realize that they are limited and not in just a small area of open water.
Scientists have just observed a thought swimming through the brain of a live fish, and that thought concerned getting something good to eat. Fish and other wild animals appear to think a lot about food: how to obtain it and what to consume.
What color does fish see best? Most fish can't see colors in the same way that humans can. They rely more on detecting contrast and brightness than they do on color. The colors that are easiest for fish to detect are likely the darker shades of blue, green, and violet.
Avoid putting ice cubes directly into your aquarium unless you make them with reverse osmosis or dechlorinated water. Perform small partial water changes with slightly cooler water, making sure not to drop the temperature of your aquarium too rapidly.
The wild wriggling and squirming fish do when they're hooked and pulled from the water during catch-and-release fishing isn't just an automatic response—it's a conscious reaction to the pain they feel when a hook pierces their lips, jaws, or body.
Researchers have found that fish recognize each other and gather information by eavesdropping. They're capable of remembering past social interactions that they've had with other fish, and they show affection by rubbing against each other.
“Fish are more intelligent than they appear. In many areas, such as memory, their cognitive powers match or exceed those of 'higher' vertebrates including non-human primates.” Fish's long-term memories help them keep track of complex social relationships.