Dead fish float upside down because they fill with light gases. The muscles and bones of the spine are heavier, so fish float belly up.
If excessive gas production is present in the GI tract, the gas-distended bowels can result in a fish swimming “belly up.” However, if fluid or foreign objects are found within the bowels, it can also result in a negative buoyancy disorder, where the fish is found toward the bottom of the tank.
Most fish are slightly denser than water, so sink immediately after death. However, like a drowned human, they become more buoyant over time as bacterial decomposition produces gases inside the body. Usually, enough gas builds up in body cavities to make the corpse float, like an inflated balloon.
After the fish dies there is no more DO being ingested and the air in the bladder starts to dissipate, causing the fish to sink to the bottom. After a few days, the internal organs of the dead fish decompose and a gas is formed. This gas causes the fish to once again float.
This can be due to overeating, overconsumption, low water temperatures, bacterial infections, parasites, or other impaired organs affecting the bladder. In these particular cases, the fish can end up with a distended belly, curved back, impaired swimming, or even death leaving them floating on top of the water.
Check the fish's eyes.
Look at the eye as a whole. If they're sunken, your fish is dead or near death. Look for cloudy pupils, which is also a sign of death in most aquarium fish. If your fish is a pufferfish, walleye, rabbit fish, or scorpionfish, occasional eye cloudiness might actually be normal.
A few signs of a sick and dying fish are if they have trouble breathing, erratic movements, pale body color, or loss of appetite. These symptoms can be a result of incorrect water parameters, water temperature, stress, or injuries. Also, keep in mind that fish die of old age, too.
The most efficient way to rid your aquarium of pollution from a dead fish is by exchanging some of its water. You won't need to clean the entire tank, but removing any contaminants that could have leached into the water is critical.
Fish can drift considerable distances downstream after they have died in a river. This can make it difficult to identify dead fish, and the exact site and time of death from telemetry studies. Furthermore, dead fish can be moved within the river, or taken out of the river, by scavengers.
Some species play dead to fool other fish, often targeting scavengers as a food source. The Central American cichlid is a perfect example. In other species, though, this behavior might hint at a health issue.
Whiting, for example, go into rigor very quickly and may be completely stiff one hour after death, whereas redfish stored under the same conditions may take as long as 22 hours to develop full rigor. Trawled codling, 18-22 inches long, gutted and stored in ice, usually take 2-8 hours to go into rigor.
Usually, your fish go to the surface when they're not getting enough oxygen. Unlike you, fish use their gills to breathe the air that's already in the water. However, in some circumstances, there's not enough oxygen in the tank for all the fish to breathe easily.
If you notice dead fish and wildlife, DO NOT TOUCH OR HANDLE THEM; simply let us know by providing the following information. Please report sick or dead bats using the White-nose Syndrome Reporting Form.
The short answer is no. Fish don't get sad over the death of their tank mates like humans do. However, they exhibit certain behaviors that lead people to speculate that they are mourning the death of their finned friends. Find out more about this here and what to do when one of your fish dies.
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.
Place the goldfish in a container filled with cool water from his tank. The cool water contains oxygen and will help to revive your fish. Some experts also suggest placing your goldfish right back into the water in his tank, even if he appears dried out.
Talk about the depth of the relationship that you shared with your pet, how meaningful it was to have him or her, and how sad you are to have lost them. You can even write a eulogy for your fish and read it to someone who supports you.
Stress is the number one cause for constantly dying fish, subsequently caused by many reasons related to water quality, unsuitable water parameters, poor aquarium ecosystem, poor fish acclimation, and aggression from other fish, to mention a few.
Loss of appetite. Weakness or listlessness. Loss of balance or buoyancy control, floating upside down, or 'sitting' on the tank floor (most fish are normally only slightly negatively-buoyant and it takes little effort to maintain position in the water column) Erratic/spiral swimming or shimmying.
It's not common to see any eye movement in fish anyway, so when looking for signs of a seizure, focus on the twitching and jerky movements of the body. Your fish may exhibit other signs, such as shortness of breath, when experiencing a seizure.
One very common reason for your fish to lay on the bottom of the tank is sickness. If the fish has contracted a disease or is infected by parasites, it will be weakened and could lay on the substrate. There are lots of fish diseases that could cause your fish to become lethargic, including: Ich (White Spot Disease)
Very fresh fish still have their neurons fully intact, even though they're dead. As soon as you add a bit of salt to the exposed muscles, the neurons are triggered and the muscles contract. So very dead fish will continue to move about until they use up all their energy stores.
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.