why do fish float when they die?

Answer 1

initially they normally sink unless their swim bladder is filled with air, soon after death the gases caused from the bacteria digesting their flesh not being able to escape causes them to float, if left they then explode if left long enough!

Answer 2

Because when the fish dies all of it's Internal organ stops working so a lot of gases can go into the fish because no any of the Organs can't stop the gases or the air that goes into the fish body so when the fish is die and full of gas. It floats. This is like when the Big Ballons fly. It uses the gas from the Fire to float but the fish dies and receives the gas from the water. Not from the fire

Answer 3

The answer to your question is two-fold. For one, fish have a swim bladder which helps them maintain different depths. When the fish dies it no longer has control over the bladder and will float on the surface if sufficient air remains in the organ.

Secondly, after death the body's tissues and immune defenses degrade. Bacteria living in the gut (and from the environment too) enter these tissues and take to feasting on everything in site. Most of these bacteria are *anaerobes* (can't live in the presence of O2). They release gases including CO2, H2, and methane, among others, as they digest fats, proteins, and carbohydrates from the fish. The entrapment of gas in dead tissues can also cause the fish to float on the surface. Note however, that it make take some time for sufficient gas to build up.

While death certainly leads to dramatic changes in the body, alterations in overall density are likely to be slight. The above two reasons are the primary ones for why dead fish float.

-L. Bry, MadSci Admin

Answer 4

Buoyancy is defined as the ability to float or to keep something afloat. As you know, air is lighter than water. Anything that traps air will tend to give the object a degree of buoyancy in water. A scuba diver adjusts his/her buoyancy level in the water by controlling the amount of air in his equipment (vest). In the same way, the fish can do so by the use of the air bladder. Some seaweeds, eg Sargassum weeds, have air sacs to keep themselves afloat.
When a fish dies, it undergoes decay where gases are produced inside the fish that causes it to bloat and rise to the surface. As most of the internal organs are intact in a 'fresh' dead fish, these gases cannot escape through organs such as the stomach or air bladder till these organs get damage. Subsequently, it may sink when the gases have a means of escaping and the dead fish loses its buoyancy.

Answer 5

I heard it is because fish have A swim bladder that helps them stay at diffrent levles in the water. When they die they lose control of it, then float. Also, sometimes bacteria in dead fish release enofe gasses to make the fish float.

Answer 6

The bacteria in their bodies begins to feed on the tissues as they break down. These organisms respire and release gases that are trapped within the fish's body, causing the mass of the fish to be less than the mass of the water, which then causes it to float.

Answer 7

gasses get stuck inside their body and the fish isnt trying to propel its self down to the bottom. If a fish stops swimming constantly it floats

Answer 8

The swim bladder relaxes, allowing the gases within to expand, and the fish as a whole becomes less dense than the water around it.

Answer 9

Their bodies bloat and fill with more water, lowering their density and making them float.

Human bodies do the same thing. They will sink if they are oxygen deprived (Lungs are empty) but will float after a while as the water gets absorbes and their density changes.

Answer 10

thats easy

they can folat to the top when alive yes mine do it when sleeping, also if they are over fed it messes with there swim bladder so the float untill they pass all the food.

as for when they are dead i have seen many sink to the bottom. i think it is to do with traped gesses that makes them folat at first then when the gass is slowley released they sink.
it is the same in people who die in water, they float then sink