10 Reasons Why Cardinal Tetras Die

The cardinal tetra is a beautiful fish often present in home aquariums. Once you bring fish home, it becomes a family member. So, losing a family member is very painful. However, many people do not understand why most cardinal tetras die all of a sudden.

The first reason that cardinal tetra dies is poor water quality. If the water in your aquarium is dirty or has high levels of ammonia or nitrite, the cardinal tetra will stress out a lot. If you fail to improve the water quality quickly, this will lead to disease and death in your cardinal tetra.

Besides this, there are many different diseases that can kill cardinal tetra. These diseases include ich, fin rot, and bacterial septicemia. Today, we will talk about all the reasons why cardinal tetra dies.

How Long Do Cardinal Tetras Live?

The average lifespan of a cardinal tetra is around three years. However, there have been reports of them living for up to six years in captivity.

Why Do Cardinal Tetras Die?

There are several reasons why this happens. Below are eleven of the most common causes:

Intestinal Blockages

When a fish ingests something it cannot digest, it can form an intestinal blockage. This often happens when they eat too many of the wrong things (like flake food).


Infections can occur from a variety of sources, including bacteria, parasites, and fungus. Some of the most common infections are ich, velvet, and neon tetra disease.


Stress is one of the leading causes of death in aquarium fish. It can occur due to many things, such as the aquarium not having enough hiding places, sudden changes in water conditions or temperature, and/or tank mates that are too aggressive.


Dropsy is a serious condition that causes the fish’s body to fill with fluid, making it look like a pine cone. Unfortunately, there is no cure for this disease and the fish will eventually die.


This condition occurs when parasites burrow into the fishes’ head causing damage to its organs. Dropsy often accompanies a hole in the head because of an internal infection.

Anchor Worm

This is a parasitic infestation that causes white spots to appear on the fish’s body. The worm attaches itself with its mouth and begins sucking nutrients from the host (in this case, your Cardinal Tetra).

Poor Water Quality

Your water needs to be clean in order for your tetras to stay healthy. They are very sensitive to ammonia, nitrite, and high levels of nitrate. The pH also needs to be stable in order for them to survive.

Cardinal Tetra Disease

There is a disease- Neon Tetra Disease (NTD) that can clear your entire tank. It attacks the fishes’ nervous system and causes paralysis within hours of infection.

Lack of Diversity

Keeping all cardinal tetras in one tank puts them at risk for illness, as well as genetic deformities like bent spines and curved tails. It’s best to mix them up with other fish species.

Old Age

Unfortunately, all animals die at some point and cardinal tetras are no exception. The average lifespan for these fish is about two years.

How Can You Know Cardinal Tetras Are About To Die?

Dying fish shows signs some peculiar and some very common. One of the most common signs is when a Cardinal Tetra fish stays on its side and has difficulty staying upright. In this case, you might to take an expert’s opinion as soon as possible.

Some more subtle indications can be:

  • Fish lying flat at the bottom or close to objects in the aquarium;
  • Fish swimming slowly or not at all;
  • Lack of appetite, refusal to take food;
  • Inflamed gills;
  • Bulging eyes (especially in Bettas);
  • Reddening skin or scales (this is usually a sign of bacterial infection).

If you see any of these signs it would be best to euthanize your fish before it suffers.

How To Prevent Cardinal Tetras Death?

Cardinal Tetras are one of the most common fish in aquariums. These small but lively fish come from some isolated rivers and tributaries in South America, which means that they can be very sensitive to changes in water quality. When you keep them at home, it is imperative for you to ensure their safety by providing them with the best possible environment and care.

Here are a few tips to increase the health and well-being of your cardinal tetras and help prevent their premature death:

Provide Plenty Of Hiding Places

Cardinal tetras are shy fish and like to hide in plants or among the rocks in their tank. Make sure to provide them with plenty of places to hide so they feel safe and secure. You can do this by adding artificial plants, rock formations, or caves to your tank.

Keep The Water Clean

Cardinal tetras need clean water to thrive, so make sure to change 25% of the tank’s water at least once a week. You should also use an appropriate filter to keep the water circulating and free of debris.

Don’t Overfeed Them

It is important not to overfeed your cardinal tetras because this can lead to poor water quality. A good rule of thumb is to feed them only as much food as they can eat in two minutes.

Monitor The Temperature Of The Water

Cardinal tetras prefer cool water temperatures between 78 and 81 degrees Fahrenheit, so make sure the temperature of your tank is within that range.

Light The Tank Properly

Cardinal tetras need plenty of light to thrive, so make sure there is proper lighting in your tank. You can do this by adding an aquarium lamp or LED light strip.

Keep The Tank Away From Windows And Doors

Direct sunlight and drafts from open windows or doors can cause fluctuations in the water temperature, which is bad for cardinal tetras. Make sure to keep your tank away from these sources of light and heat.

By following these simple tips, you will be able to provide a good environment for your cardinals while also helping prevent their death.

Some FAQs

Will A Dead Cardinal Tetra Affect Other Fish?

No, a dead cardinal tetra will not affect other fish. When one of these fish die, their body will decompose and release toxins into the water. However, these toxins are not harmful to other fish in the tank.

What Should I Do If I Find A Dead Cardinal Tetra?

If you find a dead cardinal tetra, remove it from the tank as soon as possible. If this fish has died recently, there is still some time before its body will release toxins into the water.

What To Do With The Body Of A Dead Cardinal Tetra?

Your best option for disposing of a dead cardinals’ body is to flush it down the toilet. This will ensure that proper disposal of the body and will not harm any other fish in your tank.

Can I Use A Dead Cardinal Tetra For Bait?

No, you should not use a dead cardinal tetra for bait. When these fish die, their bodies release toxins into the water. These toxins are not safe for other fish or animals.


Summing up, there are many reasons why cardinal tetra may die. Some of the more common causes include poor water quality, malnutrition, and exposure to toxins. If you are concerned that your fish may be sick or dying, it is important to take a close look at the aquarium conditions and try to identify any potential problems. With some detective work, you may be able to save your beloved fish.

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