Fish Facts

Do Fish Always Float When They Die?

If you notice a dead fish floating in your aquarium, you should the reasons behind this. Here are the 7 interesting facts that explain why and how can a fish float if it dies.

Do Fish Always Float When They Die? Yes, fish float after dying for a while. The swim bladder has an essential role in fish buoyancy both in dead and live conditions. Their body first floats when fish die, then sink toward the bottom and decompose. The decomposition process completes in around 3-4 days or a couple of weeks and then floats due to gas inflation. Most of the time, the fish body is denser than the water, so it immediately goes down after its death.

Do Fish Always Float When They Die?

Fish species can live almost 25-30 years like goldfish can live approximately 10-15 years. Sometimes aquarists are unaware of taking care of their aquatic pet like fish and other inhabitants properly, which results in fish death before its complete lifespan.

Fish is naturally buoyant, which means pressure exert against it to make it sink or equal to the inside fish pressure, which gives them the float reason.

With depth, the water force increases. The oxygen level also determines the fish buoyancy. Fish do not permanently float on the water surface, but these are settling down for a while until gas build. 

The fish die-off phenomenon stops as it starts, and the dead fish disappear after a while in few days immediately. In normal, thousands of fish die-off in the natural cascades and sink to the bottom and missing.

Why dead fish float?

When fish die, they usually float on the water surface due to air in the swim bladder. The swim bladder’s primary purpose is that the fish need it to float and swim upright direction. The air bladder fills up with the DO (dissolved oxygen) and becomes buoyant.

Bacteria are responsible for the dead body decomposition and releasing most of the gases produced in the body cavity, leading it to float. This term is also known as the inflated balloon.

Die-off results in the upside float because most of them are pretty heavy and organ directed toward the downside filled with gases.

When the body decomposes, the gas build-up results in the fish floating again on the water surface.

Usually, dissolved oxygen level ranges in the lakes from high to low, about 3 to 1. If the water level is drop-down, it becomes a severe problem for fish.

Can Dead Fish Sink?

When fish is sick or injured, their movement becomes not normal, so they float either on their side or upside down. They lose their capability to maintain the water pressure normal, and instead of buoyancy, they start to float on the water surface.

They lose all their activities when they die and float or sink immediately. It is not essential that after death, they become float and then drown in water. Sometimes, fish air bladders have no air, which causes them to float, so they immediately move downwards.

Fish sink because no dissolved oxygen ingests in the swim bladder, and air releases slowly. You can also release the air from the fish with the needle help and squeeze the body gently to release out air from the abdomen in bubble form.

In cold water, the whole process requires 8-14 days, while in hot water, the time goes down like 3-4 days.

What causes a fish to die suddenly?

If you suddenly put the fish in your aquarium, then these tiny creatures become stress or depress. You can overcome this situation by aquarium recycle. It means to place some beneficial bacteria into the aquarium that maintain your aquarium environment.

You can cycle it before purchasing fish. Overfeeding and aperiodic aquarium maintenance can become the reason for your fish death.

Different fish species require different types of habitat. If you disturb that habitat, it leads to stress in fish like a saltwater fish mix up with marine water fish and some like the cold water than the warm water.

It includes betta fish, which like calm water if you provide them with the strong water movement, leading to stress. The pleco fish require more space to hide if you cannot provide that environment disturb them, and the survival rate decreases with time.

In this way, African cichlid needs alkaline water; if you place them in acidic water, they cannot survive in your aquarium.

Cardinal tetras over to live in the acidic water if you provide them with the soft water leads to stress and die-off If you fail to provide them with a suitable environment.

Overpopulation leads to fish death in the aquarium. If you put too many fish in your small aquarium, it can lead to stress and die-off quickly due to suffocation.

When an excess amount of fish is available in the small aquarium, they consume the oxygen faster, so the level reduces with time.

While buying plenty of fish, you can take care, make the aquarium habitat in which species adjust with each other incompatible can cause a problem for your fish.

Decomposition of dead fish

When the gas releases out from the fish body and sinks to the bottom, the decomposition process starts at the bottom, in which dissolved oxygen has an important role.

During the decomposition process, enough gas produces and traps into the fish body, leading to the again fish floating due to abdomen inflation like a balloon.

Most of the fish contain the bone and muscle in its dorsal side, which inflates leads to the upside-down movement of your fish.

The decomposition process complete almost in 3-4 days or needs a couple of weeks depends on the bacterial process, and then floats on the water surface to gas filling in the abdomen. 

How can dead fish goes missing?

Sometimes the dead fish indicator is that you cannot find your aquatic fish in the aquarium. The fish after death is immediately going missing.

It happens mostly due to the other underwater inhabitants like another aquarium can eat that dead fish.

Sometimes these are hiding or fall inside or underside the aquatic plants or bury in the gravel substrate. If your aquarium lid does not cover may possible that they fall outside. Inspect the filter surroundings and the filter inlet. 

The physical appearance of dead fish

You can find out with their eyes, skin appearance. You check them carefully that these are alive or not. Their eyes color goes to change like grey or sink, which shows that they die from several hours.

Skin color also changes like goldfish color turns into white and starts to decomposes. You can check the fish gill’s movement so that they breathe or not.

Another way to check that fish is dead or not through soft touch; if these are still moving means, they are alive. 

How to tackle the dead fish?

If the dead fish remain in the tank for prolong time, it becomes harmful for other aquatic pets. The infection rate is high with time and makes the aquarium water polluted. If the other fish eat the decomposing body, the risk factor becomes increasing.

You have to put the fishnet and remove out the fish from aquarium water. Then pack the fish in the paper bag and bury it somewhere. You should get rid of a dead fish in a respectable way.

Avoid the flush out or throw in the garbage because it is harmful to water. It can transmit diseases to other pets if they eat it. If you flush out the fish, it can stick in the plumbing if the fish is large and transmit diseases and foul-smelling in the water system.

Final words:

You have to take some preventive measures when dead fish is present in the aquarium. Water quality can be disturbed due to this, so make the change to remove the deadly toxins from the water.

You can vacuum or clean the gravel substrate and add some probiotic bacteria that benefit the other aquatic inhabitants.

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