At first, the question sounds almost ridiculous: Can a fish drown in water? Fish are born to swim, after all. Yet science reveals a surprising truth: fish can indeed ‘drown’, though not in the way humans
do.
While humans drown when water fills their lungs, fish depend on oxygen dissolved in water. Through their delicate gills, they extract oxygen as water flows past, a process known as countercurrent exchange. But when this flow is disrupted, even life underwater can turn fatal.
Fish ‘drown’ when they cannot extract enough oxygen from the water. This happens if the water is stagnant, contains low dissolved oxygen, or if the gills stop functioning properly. Dissolved oxygen in water is already low, about 1% of what is in air, and in warm water, it drops even further.
Environmental Factors That Cause Fish Suffocation
Several environmental conditions can deprive fish of oxygen:
- Marine heatwaves: Warmer water holds less oxygen, leading to mass fish deaths.
- Algae blooms: Excessive algae consume available oxygen, suffocating fish.
- Polluted water: Contaminants damage gills or reduce oxygen content.
In aquariums or ponds without aerators (oxygen pumps), fish often gasp at the surface but eventually tire and die.
Fish can also suffocate if their gills are damaged, for example, when being pulled or handled improperly. Without functional gills, oxygen cannot enter the blood, leading to death.
Scientific Records Confirm Fish Can ‘Drown’
Scientists have documented over 300 cases of fish dying from suffocation in water. Reports from Discover Wildlife, Live Science, and the University of Miami confirm: “Fish can drown, but not because water fills them; they die because they cannot get enough oxygen.”
In simple terms, when people say fish drown, they mean suffocation due to lack of oxygen, not lungs filling with water. Whether due to polluted habitats, stagnant waters, or damaged gills, fish rely entirely on oxygen-rich water to live, and without it, even nature’s most perfectly adapted swimmers can quietly suffocate.
