Why Do Tetras Die? (Primary Reasons)

Why Do Tetras Die? (Primary Reasons)

Image of a black skirt tetra

The most common reasons for the untimely death of tetras are stress, unfavorable living conditions, contaminated water, constant bullying, illness, starvation, overcrowding, overfeeding, and tank water that’s not cycled properly. Apart from these, tetras die of old age after living a full life.

In the wild, tetras mainly die due to predation. However, they can live a long life in captivity if you provide them with suitable living conditions. You can easily avoid tetras’ death if you know the reasons for their death. So, keep reading to gain insights into why they die.

Reasons Why Tetras Die

Tetras can die due to various reasons.

However, when tetras start dying suddenly, it becomes necessary to determine the reasons.

Understanding the most common reasons for tetras’ death can help you to avoid it.


Stress is the primary reason for tetras to die. An overly stressed tetra will eventually die.

Hence, managing stress is the key to living a long and healthy life. Several factors can cause stress to tetras.

Tetras can feel stress due to constant bullying, poor water conditions, unfavorable water parameters, space constraints, or illness.

You can observe a change in your tetras’ behavior if they are stressed.

When stressed, tetras will lose their appetite – leading to weight loss, swim frantically up and down the sides of the aquarium, and hide more often.

Unsuitable aquarium set up.

A favorable environment is a key to live a long life for any fish.

You need to set up an aquarium by keeping the requirements of tetras in mind.

Tetras are tropical fish. They need warm water to thrive. If the water is too cold, it can stress them.

Stress can lead to a drop in the immune system, slow metabolism, lack of appetite, and heart problems in tetras.

They can die if exposed to stress for a prolonged duration.

Similarly, tetras are freshwater fish. Hence, if you have a saltwater aquarium, tetras cannot survive for long.

Tetras can live in water with some salt but cannot survive in the saltwater aquarium for too long.

Poor water conditions.

Poor water conditions are another primary reason for the premature death of tetras.

The water quality is of utmost importance for the healthy growth of tetras.

Tank water can be contaminated by an increase in the levels of ammonia, nitrates, or nitrites.

Besides, water can get polluted due to unremoved leftover food, fish waste, insufficient filtration, or lack of water changes.

The water temperature, pH levels, salinity, filtration, and water parameters need to be ideal.

If even one of the parameters is not ideal, it can be a reason for the early death of tetras.

Overcrowded tank.

An overcrowded tank is another reason for tetras to die. It’s basically a death sentence for your fish.

If your tank is overcrowded, it means the tetras will not be able to swim freely.

Space constraints can cause stress to tetras, leading to their premature death.

Besides, if you have an overcrowded tank, the oxygen depletion will be faster.

Low oxygen levels can suffocate the tetras.

Also, the more the number of tetras, the more will be the waste created.

If the tank water is polluted, tetras may not be able to cope with the toxins and will eventually die.

Rapid water changes.

Rapid water changes can also lead to the death of tetras.

Rapidly changing massive quantities of water results in rapid swings of the water temperature and pH levels.

This can shock your tetras, which will soon lead to their death.

Besides, rapidly changing the water disrupts the natural chemistry of the tank water.

Tetras cannot adjust to sudden changes in the water chemistry leading to their unexpected death.

Hence, the water change process should always be slow and steady.


Overfeeding is another common reason for tetras’ untimely death.

The more you feed your tetras, the more will be the waste produced in the tank water.

Leftover food, if not removed, results in contaminated water. Toxins are created in the tank water, which can kill the tetras.

Drastic changes in water temperature.

Most of the tetras can tolerate a range of water temperatures.

If the water temperature changes drastically, it can stress the tetras, leading to their death.

Water temperature plays a vital role in aquatic life.

Thermal pollution or heat transfer from direct sunlight can fluctuate the water temperature.

Temperature shock happens when the water temperature of the tank deviates too rapidly from the ideal conditions.

The water temperature change can be either too high or too low.

Colder temperatures are more likely to be the cause of death for tropical fish like tetras.

If the water temperature deviates a lot from the ideal range, it impacts the metabolism and immune system of the tetras.

The metabolism slows down, which results in sluggishness and stress to tetras.

Your tetras may then die due to stressful conditions.


Diseases and illnesses are other primary reasons for the untimely death of tetras.

Any fish, including tetras, are exposed to a wide variety of infections and diseases.

If your tetra is suffering from a disease, it needs special care.

If proper care and medication are not provided to the sick tetra, it may die eventually.

The first thing you will notice is that your tetra is isolating itself when it is sick.

Some of the other symptoms you can observe are restlessness, difficulty in swimming, bloating or fin rot, loss of color, buoyancy loss, lethargy, weakness, and appetite loss.

Incompatible tankmates.

Not all fish species get along with each other.

When you have a community tank, you need to ensure that all fish live in harmony with each other.

Tetras are small peaceful fish.

Hence, if you have aggressive fish like cichlids, your timid tetras will be continuously under stress due to bullying.

Being always chased and nipped by aggressive tankmates is stressful and can lead to the untimely death of tetras.

Unexpected toxins.

Toxins is yet another reason for the early death of tetras.

Tetras are susceptible to toxic contaminants such as soap, hand lotion, perfume, bug spray, or other cleaning chemicals.

If the tank water gets contaminated accidentally with these substances, your tetras may suffer and die.

Rough travel.

Tetras are tiny fish that need delicate handling.

If your tetras had a rough journey from the pet store to your aquarium, they might get stressed by the long journey.

Usually, we bring fish home in a plastic bag that contains limited oxygen.

Hence, if the travel is long, it becomes quite traumatic to the tetras. They can die due to excessive stress.

Tank not cycled properly.

Every fish tank needs to be cycled before you can add fish to it. Cycling refers to the nitrogen cycle in the aquarium.

It is a process through which beneficial bacteria break down the toxins like ammonia and accumulated waste into less harmful substances such as nitrates and nitrites.

The beneficial bacteria do not exist in a newly set up aquarium.

Hence, if you add tetras in the non-cycled tank, it may prove disastrous.

Your tetras can get stressed as water is not safe for them and may die eventually.

Old age.

Tetras can have a life span of 10 years in the wild.

In captivity with optimal living conditions, the average life span of tetras is around 5 to 7 years.

No fish is immortal. Hence, once they reach old age, they may die after leading a full life no matter how well you care for them.

Do Tetras Die Easily?

Tetras are hardy fish. They can live up to a decade provided they get suitable living conditions.

However, tetras are sensitive until they adjust to the new environment.

Hence, it is essential to monitor their health and the water conditions until they acclimatize to the home aquarium.

Having said that, any drastic change in water temperature, pH levels, toxic water, illness, constant bullying, or stress for a prolonged duration can cause the death of tetras.

Related Questions

Why do neon tetras die? Neon tetras die due to various natural and unnatural causes. In the wild, predation is the primary reason for their death. On the contrary, in captivity, neon tetras can die a natural death due to old age. Apart from natural death, neon tetras can die if they do not get a favorable environment. Stress, starvation, illness, suffocation due to oxygen depletion in the tank water, overfeeding, rapid water changes, drastic change in water temperature or pH levels, contaminated water, and incompatible tankmates are some of the significant reasons for their death.

Why do cardinal tetras die? Cardinal tetras are peaceful and easy to care for fish. They can live up to five years if the living conditions are suitable. However, they can die early due to stress, low water conditions, overfeeding, space constraints, lack of oxygen supply, unsuitable water parameters, bullying, or illness.

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