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.
It should also be noted that fish don't necessarily always float when they die. For example, if a fish dies with little to no air in its swim bladder, the act of dying doesn't magically make this bladder expand to increase buoyancy. In these cases, the fish will often sink, at which point decomposition will begin.
Oxygen remains in the bladder after a fish dies. Additional gases are released during decomposition. "The fish is like a closed container," says Boriek. "As the fish decomposes, gases fill the body cavity." The belly becomes a guts-filled balloon and the fish floats to the surface.
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.
It's pretty easy to tell when fish are sleeping: they lie motionless, often at the bottom or near the surface of the water. They are slow to respond to things going on around them, or may not respond at all (see some sleeping catfish here). If you watch their gills, you'll notice they're breathing very slowly.
Any dead fish should be removed, as its body will quickly rot in the warm, bacteria-laden water. A corpse will pollute water, risking the health of other fish in the tank. If it died from disease the last thing you want is other fish consuming its body parts, so remove immediately.
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. Overinflation usually takes place in the posterior chamber.
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.
Why Is My Fish Swimming Upside Down? 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.
Fish often remain unusually still after a fellow dies in the same aquarium. Researchers say this behavior is probably due to stress hormones released into the water by the dying fish.
The general rule of thumb is that if a fish has been properly handled and stored, you can safely eat it up to three days after it has died. This time frame also applies to cooking it or freezing it for later consumption.
If your skin is easily irritated, avoid red tide water. If you experience irritation, get out and thoroughly wash off with fresh water. Swimming near dead fish is not recommended.
If you've noticed your fish struggling to stay afloat, sinking or even swimming upside down, it's likely that your fish is suffering from swim bladder disorder.
Poor water conditions
Whenever the tank has bad water or water not suitable for the fish's health, it leads to their death. Poor water condition is a big reason why most of the fish die in a fish tank. Therefore, if you are an aquarist, the priority should always be to maintain the water quality.
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.
You're not supposed to flush the fish down the toilet, so how can you properly dispose of it? If unsure what to do with a dead fish, one option is to put it in a plastic bag and bury it in your backyard. You can also throw it into the garbage or even consider cremating your fish as well.
Most fish sink to the bottom of their habitats when they die but they become more buoyant as the process of decomposition takes over. Most fish are slightly denser than water, so sink immediately after death.
As soon as a fish dies, the other fish in the tank will begin feasting on their former friend. It's not personal; it's nature. Don't assume they murdered their former tank mate. They are just taking the opportunity to have a fresh meal.
When you see your fish belly-up, don't assume it's dead; if it's still breathing, it probably has swim bladder disorder. Here are symptoms to look for: The fish keeps floating to the top, upside-down. The fish keeps sinking to the bottom of the tank.
It's more often that a fish will die from overfeeding rather than die from being starved. This would be the case as not all the food put into the tank would be eaten or removed. This food is likely to fall to the bottom of the tank and stay there, where it will begin to rot over time.
Fish become frustrated and unhappy when kept in cramped bowls or tanks. House fish in a large filtered tank. All tanks should have a pump to keep water flowing continuously.
If your fish is swimming frantically without going anywhere, crashing at the bottom of his tank, rubbing himself on gravel or rocks, or locking his fins at his side, he may be experiencing significant stress.