Home Fish Facts Can Fish Have Heart Attacks? (Explained for Everyone)

Can Fish Have Heart Attacks? (Explained for Everyone)

by gvald

Even though fish are not made up in the same way as we are, as long as they have a heart, it is quite possible to have a heart attack. Some people don’t call it that.


A heart attack is considered to be when the blood can no longer make its way to the heart. This is not always the reason why the heart stops in fish, but for simplicity’s sake, most people call it a heart attack in fish.


Why can a fish die of a heart attack?

Ammonia poisoning is the number one cause of death in aquarium fish. Typically, there is a sharp rise in ammonia just after an aquarium is set up for the first time.


However, an ammonia surge is also possible in an older aquarium if it is too small and/or overcrowded or poorly maintained (e.g. no water changes), after a prolonged power outage (during which the bacteria in the filter died), or because of a filter failure or inadequate filtration for the volume of water.


How do you know if your fish died of a heart attack?

Most fish species have gills that move, a sign that they are breathing. So if your fish’s gills are not moving, it is likely that it is dead.


But be aware that some species, like fighting fish, breathe through their mouths. If this is the case with your fish, check its body movements.


When the water in the aquarium is too cold, it can put the fish into a kind of hibernation. So, consider checking the water temperature as well as its toxicity.

Indeed, if the water is too high in nitrite, your fish may have become intoxicated and is therefore ill. In this case, a change of water is necessary.


How to see if your fish is in cardiac arrest?

To be honest, there is very little chance that you will be in front of your fish when it has a heart attack, it rarely lasts more than a few seconds.


And even if you do, it is almost impossible to recognize a fish that is having trouble, here are some tips just in case:


1. Pay special attention to its eyes

You may have a hard time seeing its eyes. If you have some time, you should be able to examine them. Look through the aquarium until it gets close enough for you to see its eyes.


  • Abnormal bulging, mucus buildup or eyes that appear opaque may be signs that he has a problem.
  • Protruding eyes can be a sign of “bulging eyes,” which is usually due to an infection.
  • If his eyes are dull or have an opaque film over them, it may indicate that he has a vitamin deficiency.


2. Pay attention to how he swims

Look at it for a few minutes to see if it swims at an angle, upside down or in any other unusual way. Normally, these animals swim in an upright position and stay closer to the bottom of the aquarium. Therefore, anything significantly different could indicate that he is doing poorly.


Likewise, make sure he is swimming and interacting with objects in the aquarium. If it barely moves and stays at the bottom of the tank, it’s a sign that something is really wrong.

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