Check the fish's eyes. 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.
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.
One common sign that a fish is dying is that it'll be gasping for air. If your fish is gasping for air, it could be caused by the following: There's not enough oxygen in the water. The water is high in ammonia.
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.
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.
In many cases, the fish isn't actually dead but rather suffering from a problem with their swim bladder due to overfeeding. There are plenty of warnings about overfeeding fish, but many people are unaware of just how easy it is to overfeed.
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.
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.
"As the fish decomposes, gases fill the body cavity." The belly becomes a guts-filled balloon and the fish floats to the surface. Most of a fish's mass is bone and muscle on its dorsal side, so as the belly balloon rises, fish tend to flip upside down. Fish don't always float to the surface right away.
If you see your fish lying on the substrate, gasping for breath, that could indicate the beginnings of nitrate poisoning, and you'll need to do an immediate water change.
They could also be bottom sitting due to water conditions, parasites or bacteria, stress, or gastrointestinal problems. If they are bottom sitting due to water conditions, then this needs to be corrected with checking the water daily and doing large water changes until the water is within appropriate parameters.
If you experience irritation, get out of the water and thoroughly wash off. Do not swim among dead fish because they can be associated with harmful bacteria.
A fish should be removed from the tank immediately after death. Of course, you may notice the incident right away but it is important to remove the fish as soon as it is noticed. This is because a fish will start to decompose right away and will release harmful toxins into the tank.
All that swimming by the dead fish is powered entirely by the energy in the moving water. Of course, evolution being what it is - real - sea creatures have evolved to take advantage of getting a energy boost from the water moving around them, and not just when they're dead. Most fish have a "lateral line".
Some fish succumb to pH shock immediately. Others may exhibit symptoms including thrashing, darting, gasping, swimming near the water's surface and trying to jump out of the tank. Such symptoms are the same as those that indicate toxins in the water -- either cause is serious.
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.
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.
A few reasons include stress, incorrect tank setup, overfeeding, diseases, and much more. To a beginner, it could look like your fish died for no reason whatsoever.
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.
Buoyancy problems are caused by a wide variety of disorders. Some of these include systemic disease (bacterial, viral, fungal, parasitic, cancer), starvation, general weakness, eroded fins and broken fins, swim bladder diseases, and excessive air in the gastrointestinal tract or abdominal cavity.
Large water changes that include more than 60% water change, rinsing gravel, cleaning filter media lead to a complete, massive change in the water chemistry. Fishes when put in these new conditions, lead to temperature shock, stress, loss of appetite, and then death.
To protect themselves, fish will instinctively hide when they are uncertain, frightened, stressed or uncomfortable. Having a safe place to retreat provides comfort and security, and greatly improves a fish's chance of surviving in the wild.
Strange Swimming: When fish are stressed, they often develop odd swimming patterns. 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.