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.
Some fish can survive for a few minutes out of water, some for a few hours, and some for even a few months! This mostly depends on the species of fish, the habitat/environment, and how long you fight the fish.
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.
The majority of the animal kingdom, including fish but not dolphins, do not have a sense of identity or self-recognition [1]. So they likely do not experience an abstract awareness of their eminent demise.
Most dying fish can be easily revived with changes to the water. Maintaining water quality is essential to keeping your fish happy and healthy—and alive. You can buy a fish tank water testing kit at most pet stores. These tests can help you identify any problems with the water, such as high ammonia.
Swim bladder disease is when a fish loses its ability to regulate the air going in and out of its swim bladder. This causes the fish to swim strangely, on its side, or even upside down.
That said, the decomposition process can sometimes result in enough gas being produced and trapped inside the fish to cause it to float to the surface. So in short, fish float upside when they die because many of them are top heavy and posses an organ in their lower region that is filled with air.
As previously mentioned, immediately after death, motor neurons maintain some membrane potential, or difference in ion charge, which then starts a domino effect down neural pathways causing movement.
When the water doesn't have oxygen, they suffocate, just like humans suffocate when we don't breathe enough oxygen. So, while a fish can't die from drowning in water, it can die from suffocating in water due to a lack of oxygen.
The most common cause of fish kills is suffocation due to lack of dissolved oxygen. Most dissolved oxygen is produced by algae and aquatic plants through photosynthesis. A lesser but also important source of oxygen in water is diffusion from the atmosphere, which is enhanced by wind-induced surface water turbulence.
Usually the conditions that caused the fish kill will not last for more than a few days. Repeated fish kills and chronically low dissolved oxygen levels may necessitate the installation of an aeration system designed to maintain healthier DO levels.
At depth, the gasses in the swim bladder are at equal pressure. When the fish is reeled up to the surface, the gasses expand and can cause the eyes to become bulged, cloudy or crystallized and the stomach to protrude out of the mouth. Although one might suspect that the fish is dead- it's not.
The two biggest reasons for fish illness are stress and dirty water. While some healthy fish can fight off the infection and get healthy, the weak ones may die. Therefore, it is important to watch for the signs of stress in your fish. Ich– It is a parasitic infection that passes in one fish from another fish.
Yes, you can treat new fish using the level 1 low salt dosage for 2 weeks. This solution should eradicate roughly 60% of potential illnesses. You can also use this technique for healing any fish that got beat up and needs some solitary recovery time in a hospital tank.
A species of tropical fish has been shown to be able to distinguish between human faces. It is the first time fish have demonstrated this ability.
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.
Instead, these sharks rely on obligate ram ventilation, a way of breathing that requires sharks to swim with their mouths open. The faster they swim, the more water is pushed through their gills. If they stop swimming, they stop receiving oxygen. They move or die.
Positive buoyancy disorder, where the fish floats at the surface or on its side, is the most commonly presented form of swim bladder disease, especially in goldfish. Most likely, the cause is overinflation of the swim bladder.
If your fish is swimming upside down, it has a problem with its swim bladder. Your fish has stopped being able to control its swim bladder and has got stuck with too much air inside it. The reason for this could be constipation, a poor diet, eating habits, or an infection.
If fish are experiencing acute stress (i.e., gasping up at the surface, lying on the bottom and not moving, or darting around the aquarium), you can be pretty sure that the water has been poisoned in some way. Maybe cleaning sprays got into the aquarium, or something released toxins into the water.
Verifying Death
Veterinarians and biologists consider a fish to be dead 10 minutes after the last sign of gill movement. It is important not to remove a fish for disposal until death has been established.
Fish may die of old age, starvation, body injury, stress, suffocation, water pollution, diseases, parasites, predation, toxic algae, severe weather, and other reasons. A few dead fish floating on the surface of a pond or lake is not necessarily cause for alarm.