It gets necessary oxygen required to live in, from water through tiny blood vessels spread over the surface area of its gill and not from air. Though some fish can breathe on land taking oxygen from air, most of the fish, when taken out of water, suffocate and die.
According to Collins Concise Dictionary, drowning is “to die or kill by immersion in liquid” – so no, fish cannot drown. However, they can suffocate when fresh water does not contain enough dissolved oxygen – either as a result of eutrophication (an excess of nutrients) or drought.
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 faster they swim, the more water is pushed through their gills. If they stop swimming, they stop receiving oxygen. They move or die.
To revive a dead fish, the most common method is to submerge it in a bowl of iced cold water. This will cause the fish to go into shock and (hopefully) come back to life.
Fish out of water are unable to breathe, and they slowly suffocate and die. Just as drowning is painful for humans, this experience is most likely painful for fish. Compounds like cortisol—the hormone associated with stress—can significantly increase during periods when fish are out of water.
The differences in acidity and dissolved oxygen, not to mention all of the fat, proteins, carbohydrates, and other minerals in the milk that might clog the creature's gills, would quickly spell trouble. The animal would likely die within minutes, if not sooner.
Fish have gills that allow them to “breathe” oxygen dissolved in the water. Water enters the mouth, passes over the gills, and exits the body through a special opening. This keeps an adequate amount of water in their bodies and they don't feel thirsty.
Yes, fish can hear you talk!
Sounds that are created above water typically do not carry enough force to penetrate the surface tension of the water, so talking on the boat or loud noise may not affect fish as much as your fellow anglers may want you to think. Your voice is unlikely to spook or scare fish away.
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.
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.
Air asphyxiation
One Dutch study found that it took 55–250 minutes for various species of fish to become insensible during asphyxiation. Fish that evolved for low-oxygen environments take longer to die. At higher temperatures, fish lose consciousness more quickly.
Although some fish can pump water across their gills while at rest, many fish must swim constantly so that water flows past them. If they get trapped, such as in a fishing net, they may get stuck and suffocate, Withrow told Live Science.
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.
Yes, fish experience both physical and emotional pain. Scientists say that it's likely a different type than what humans experience, but it's pain nonetheless. Fish have nerve cell endings called nociceptors, which alert their bodies to potential harm such as high temperatures, intense pressure, and harmful chemicals.
Fish-keepers sometimes see their pets 'glass surfing' – swimming repeatedly up and down the glass of the tank. This could be the aquatic equivalent of the pacing of a captive tiger that's bored from a lack of stimulation. But the fish could also be stressed from an overcrowded or unfamiliar tank.
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.
The specialised retinas of some nocturnal coral fish result in faster vision and greater sensitivity to dim and bright light. The same adaptation may enable deep-sea animals to see in darkness.
Fish breathe by taking in the free oxygen in the water and filtering it through their gills. Coffee doesn't have the same level of oxygen as water, so the fish won't be able to breathe as well.
Out of all the "old-school" methods, this process seems most inhumane. The AVMA does not advocate freezing fish as an acceptable method of euthanasia; the only way they would approve of cooling would be to deep freeze an animal that is already under deep anesthesia.
While mammals and birds possess the prerequisite neural architecture for phenomenal consciousness, it is concluded that fish lack these essential characteristics and hence do not feel pain.
Clove Oil (contains eugenol)
Clove oil is a sedative which at high doses, can be used to euthanase small fish. Unlike veterinary anaesthetics, clove oil is readily available from most chemists. Around 0.4ml of clove oil per litre of aquarium water is sufficient to cause death in exposed fish.