Why can fish float and sink in the water?

Fish are a bit like birds or flying insects: they have a built-in mechanism that allows them to move up and down, left and right in the environment in which they live. But the method used by fish to accomplish this maneuver is closer to the principle behind man-made aircraft than natural flight methods.

Most fish float in the water in the same way that a helium or hot air balloon rises and falls in the air.

To understand how this works, you need to understand the multiple forces that work in the air and underwater. Although these environments may seem very different to us, water and air are actually very similar. Both are fluids – substances that have mass but no shape.

On Earth, an object immersed in a fluid, such as a fish or a person, experiences two main forces:

Pull down the force of gravity.

Buoyancy of pushing up.

Buoyancy is caused by the different fluid pressures at different heights in the fluid. The lower particle is pushed down by the weight of all the particles above it. Whereas, for taller particles, the total weight of its upper particles is less.

Therefore, the pressure under an object is always greater than the pressure above, and the fluid will keep pushing the object upwards. (To learn more about buoyancy, read How Hot Air Balloons Work.) ）

The buoyant force experienced by an object is equal to the gravitational force of the fluid that the object distributes. For example, if you submerge an empty 4-litre milk jug in the tub, it will drain 4-litre of water. The water in the tub is then pushed upwards by the gravity of 4 litres of water (about 4 kilograms of force).

The larger the volume of the object, the more force it has to be pushed upwards as it displaces more fluid. Of course, if the object is denser than water (and therefore heavier than water), it doesn't matter how much water it explodes – it will still sink to the bottom.

In order to rise, the fish must manage to reduce its overall density by increasing its volume without significantly increasing its mass. Most fish use an organ called a swim bladder for this purpose. A fish swim bladder is just a sac that can be inflated like a human lung.

To reduce its overall density, the fish fill the swim bladder with oxygen collected from the surrounding water through the gills. When the swim bladder is filled with oxygen, the size of the fish increases, but its weight does not increase significantly. When the swim bladder expands, it dislodges more water and is therefore subject to greater buoyancy.

When the swim bladder is fully expanded, the fish has the maximum volume and is pushed to the surface. When the swim bladder is completely emptied, the fish is smallest in size and sinks to the bottom of the sea. To maintain a certain height, the fish fills its swim bladder until the weight of the water it discharges is equal to the weight of the fish itself.

In this case, buoyancy and gravity cancel each other out, and the fish can stay at that height.

Most fish rise and fall in this way, but not all fish do. Some species of fish do not need swim bladders because they cruise along the ocean floor throughout their lives. While other fish, such as rays and sharks, float or sink by propelling themselves forward.

Because there is a swim bladder in the belly of the fish, and the fish journey through the process of tightening and relaxing the muscles, so that the swim bladder becomes smaller or larger, and the inhaled air also changes, and because the air is lighter than water, the fish uses the swim bladder to control the ups and downs.

Because there is a swim bladder, it is like a hollow cavity, which sucks in water when it descends, and discharges water when it floats up.

Fish floating on the surface of the water This condition can be caused by a number of reasons:

1. The fish have just entered the new fish tank and have not yet adapted to the new environment.

2. Flatulence of the fish, which is related to the feed eaten. It is recommended that you first see if the abdomen of the fish is swollen badly, and whether there is defecation, if there is defecation, it doesn't matter, if there is no defecation for two days, then you must puncture the fish body, and take a needle to pierce the fish belly to exhaust.

3. If there are many fish in the fish tank, it may cause hypoxia, so it is recommended to press an oxygen pump.

1. Picking good fish is one of the basic skills of raising goldfish. When picking fish, choose those fish that look round and have a bright body color, which is a healthy fish with good genes. The number of fish should be matched with your own tank, and the ideal proportion of fish in the water should be 1000

1. The body length of goldfish and the length of the fish tank should reach more than 1:10, which can ensure that the water quality of goldfish is good and the amount of dissolved oxygen is sufficient.

2. Raising water is the second basic skill of raising goldfish. A week before bringing the goldfish home, open the tank, raise the water, and put a few small fish into the tank to see if it is suitable for the goldfish to survive, so that you can also establish a nitrification system. A filtration system must be installed inside the fish tank so that the water quality can be maintained.

It is also necessary to install an aeration pump so that the fish can breathe better.

3. The choice of light is one of the important skills for raising goldfish. After the fish are in the tank, the fish tank should be placed in a place where there is sunlight for 1 2 hours. This makes use of the sun's ultraviolet rays to kill germs and also reduces diseases.

Fish diseases should be mainly prevented, supplemented by medicine. And it will make the fish colorful.

The fish floats on the surface all the time, probably due to the habits of the fish. However, most of the fish will surface due to lack of oxygen, and they can immediately change the water and increase the oxygen supply capacity. If there is a disease, such as chlorine poisoning, ammonia poisoning, nitrite poisoning, and weakened respiratory function, the fish head will also surface, and you can go to the local pet hospital for examination to find out the cause before doing it.

Why do ships float on the water.

1. Some fish have a habit of being near the surface of the water and rarely going to the bottom, such as toothed butterfly fish.

2. When the dissolved oxygen content in the water is less than 3 mg per liter, most fish will float due to lack of oxygen, and need to increase oxygen and change the water in time.

3. Chlorine poisoning, ammonia poisoning, nitrite poisoning, fish will also float due to lack of oxygen, and need to increase oxygen and change water in time.

4. Infectious gill damage, weakened respiration, fish will always surface, and it is necessary to prescribe the right medicine.

Problems to be paid attention to in fish farming

The first point is that when choosing a fish tank, its size should be reasonable, especially the location of the choice should be fully understood. There are many types of aquarium models and sizes sold on the market, so choose a fish tank with a reasonable size according to the requirements of indoor decoration and placement, so that it will be better in the process of placement.

The second point is that the choice of fish species should be decided according to the living habits or the location of the fish. The fish species placed in different locations such as living rooms and offices will also be different.

The third point is that the aquarium needs to be filtered or cleaned before it can be scientifically farmed. In terms of fish farming skills and details, all equipment systems must be cleaned, so that when cleaning up in time, I feel that the way of fish farming will be more novel.

Fish swim upstream on the surface of the water because of the lack of oxygen in the water, the high level of ammonia nitrogen in the water, the disease of the gills, foraging, and the low temperature for heating.

1. The fish swim on the surface of the water, it is likely to be caused by the lack of oxygen in the water, and the fish need sufficient oxygen in the water, and this situation will occur if there is a lack of oxygen.

2. If the ammonia nitrogen content in the water body is too high, resulting in fish poisoning, it will also make it float.

3. Gills disease will also make the fish have difficulty breathing, and their heads will float at this time, but it is not because of the low oxygen content in the water.

4. When the fish are hungry, they are looking for something to eat on the surface of the water, which is most obvious around the food table, especially the fish that live in the middle and upper layers of the water body.

5. The temperature is low in the season, and at noon on a sunny day, due to the high water temperature in the upper layer, it is a normal phenomenon for fish to float on the surface of the water, and this phenomenon will immediately disperse and sink after being frightened.

The solution for fish swimming on the surface:

1. Reduce feeding, because the metabolism of fish after full food will increase the increase in oxygen demand.

2. Replace clean water to increase oxygen content, and it is best to use an oxygen pump.

3. If the fish tank is relatively large, you can put a small eye stone in the fish tank to make a little oxygen; It is best to use an oxygen pump.

Fish don't have eyelids, and their eyes can't close at all. Still, they have to sleep regularly. Of course, they can only sleep with their eyes open.

But a variety of different fish still have their own unique way of sleeping. Some fish lean their bodies to the side when they sleep, and the current causes them to float to **.

Many fish that live in shallow waters should be placed on the bottom of the sea when they sleep. The rest of the body stands tall. There are also fish that live in reef waters.

Swim to a reef cave and hide while sleeping. It is rare to see Wu Yu sleeping. The reasoning is hard.

The light in the water was too dim at night. Most of the fish are asleep, but they are invisible to the general person. Divers must use underwater searchlights to observe the fish's naïve state when they sleep.

Fish sleep when the rays.

What does it do? Anchovy.

Lives at the bottom of the sea. But while sleeping, some species of anchovies swim into the sea. They bend their flat bodies into bowls and float with the waves in their sleep. Flatfish.

Unlike mackerel. The same as climb high when the evening comes. They can sleep by simply floating a few centimeters above the ocean floor.

Fish are able to control their swelling in the water because of the help of 2. Rays can accurately adjust the specific gravity between the fish's body and the seawater. When the stingray grows larger, the fish involuntarily climbs up. Widower.

Shrunk. Negative numbers sink to the bottom of the sea. In this way. Even without shaking the tail fin, the fish can float up and down in the water. Cartilaginous fishes.

For example, sharks) have no rays, so they have to drain their bodies in the water to rise or sink. Some sharks can sleep lying on the bottom of the sea. Therefore, keep shaking the tail fin while sleeping.

It can keep the body from sinking. There are few natural predators of big fish in the sea, so you can find a calm place to sleep, and the sleeping style is also fluctuating, so you can sleep for a short time. Of course, sharks also have special situations such as swimming when they sleep, but sometimes there are signs of rest such as sleep, but they do not enter sleep under the definition of regularity.

Many fish that need to swim are born without sleeping. There is often tuna and bonito.

If you try to tell whether you sleep or not by the movement of the fish, the results will still be disappointing. Because the gill cover can still shake slowly and rhythmically in order to breathe while the fish sleep. Sometimes shake the pectoral and caudal fins to keep your body balanced.

In addition, the fish sleep for a short period of time, only a few minutes or even seconds, which is to force the fish to be vigilant so as not to fall into the mouth of the raider. Researchers have found that fish have two sleep patterns. One pattern is known as "slow burst sleep" and may be similar to slow sleep in humans.

Another mode is labeled as "spreading sleep", which is equivalent to human fast-wave sleep.

They float in the middle of the water, and I've observed that they need to be ventilated during sleep, so they usually don't sink to the bottom of the water but are in the middle of the water, which is interesting.

It will float in the middle of the water, because once the fish sinks, it will be eaten by other fish and become food for other fish, and it is safest to float in the middle of the water.

Many fish, while sleeping, lie motionless on or near the bottom of the water. Their breathing rate slows, and they often appear groggy or unresponsive. For example:

Tilapia, zebrafish, and swollen sharks lose their responsiveness at night. Some fish spend their rest time in the corals of the reef, and when they sleep, their bodies appear to be moving or like they are swimming.

Hello, this is related to the species of fish, whether the food has not been digested, the time of death, impurities, temperature, and the amount of bacteria in the water, that is, if the average density of the fish is less than the density of the water, it will rise; If it is equal to or greater than the density of water, it will suspend or sink.

Consider it a little more complicated: because fish have an organ that regulates the specific gravity of the body - the swim bladder. When a fish dies, it loses the ability to regulate the size and specific gravity of its swim bladder.

In addition, body tissues are decomposed by microorganisms to produce gases, so they will float to the surface; If there are special circumstances, such as low temperatures (not freezing point), the fish has just eaten, and its swim bladder does not inhale too much air, etc., the average density of the fish will be higher.

The fish does not float when it first dies, and after a long time, the gas in the stomach expands and floats to the surface of the water.

There is a lack of oxygen in the water, come up and inhale oxygen.

Or died.

In my meager experience, sinking to the bottom and floating to death depend on how much qi is in the swim bladder at the moment of death.

I have raised goldfish, and I have died, but after my goldfish died, I sinked to the bottom, and I didn't find that there was a situation floating up, and small tropical fish were also raised, and I remember that there were more than 100 red women with traffic lights, and they died violently. Then there are those who float up, and there are those who sink.

Hope it helps.

Fish survive on oxygen dissolved in the water, and when the temperature rises in hot weather, the solubility of oxygen in the water decreases, and the oxygen concentration decreases.

Because there is a lot of dissolved oxygen on the surface of the water near the air, the fish need to float to the surface to breathe.

The cause of death is different, if it is congested and dies, it sinks; If it's a lack of oxygen, it's floating, that is, depending on how much gas is in the fish float.

When an object floats, it is fully immersed in the liquid. When it reaches the surface of the water, part of the mold is exposed outside the Danhe Qinshui, so the volume immersed in the water decreases, so the buoyancy decreases.

So in the end, buoyancy and gravity are equal.

Those who sink to the bottom of the water are broken, and those who float on the surface of the water are not broken.

It turns out that when you are in the deep sea, the pressure in the lungs of the fish is in balance with the outside world (seawater). After death, the lungs are not working properly, and the air pressure in the lungs decreases, so they float to the surface of the sea. a