13 Reasons Why Your Fish Keep Dying

Taking care of your fish and still watching them suffer is heartbreaking!

You might be doing everything right, and still be facing problems with the health of your fish!


Finding your fish lifeless is probably the worst sight to see for a tank owner!!

You might be asking:

Why do my fish keep dying?

Well, One of the most common reasons related to the death of your fish is stress. A lot of factors can induce stress in your fish. If the water conditions are not right, or it has an imbalanced pH level. It can cause a lot of stress in fish, which further creates more problems. It can promote weight loss, illnesses, fighting amongst each other, preferring to stay in isolation or hiding.

Dead Fish Tank Problem (Video)

We found 13 more reasons that can contribute to the death of your fish:

1- How the New Tank Syndrome might be the reason your fish keep dying

New tank syndrome is one of the first challenges you might face as a new tank owner.

Since the tank environment is new, it does not have the required minerals and the water is not as stable!

This means that the water is deficient in necessary minerals and your fish could incur harm.

Most new tanks also lack microbes and bacteria colonies, and these colonies are an essential aspect of maintaining water stability.


It takes time for plants, fish, and gravel to adjust and release extra waste into the environment.

You may need to cycle the tank until a suitable level of minerals and pH is maintained for your fish.

Otherwise, new tanks tend to cause fish stress and can promote diseases as well.

2- Is Inappropriate tank size the reason your fish are dying?

An Inappropriate tank size might also be one of the most significant contributors to the death of your fish.

You might be selecting your tank size based on the space you have in your home.

Once you have selected the area, you can then proceed with choosing the type of fish that you want in your tank.

This is perhaps one of the most important things when it comes to deciding how many fish to put in what size of the tank.

If you have a 5 to 10-inch-long fish, then it is better to put one or two of them in a 10-gallon tank

Scenario #1. When the tank is too small:

If you have smaller fish is like guppies and goldfish, you could opt for putting them in a smaller fish tank.

However, for larger breeds, the tank should spacious, and there should be room for them to explore!

More complex breeds tend to fight amongst themselves if the tank is too small.

The environment would be stressful for them to thrive and that is alarming, especially if you are a breeder.

Smaller tank size can also promote a more rampant spread of diseases and parasites.

If one of your fish gets infected with bacterial or fungal disease, it is likely that the disease will spread much more quickly

You might not have the resources to quarantine them in a smaller tank adequately.

Beyond that, this can also cause overcrowding of fish.

Small tanks might have less space available for fish and can cause them to be aggressive.

They will have more tendencies to harm each other!

Scenario #2. When the Tank is too Large:

Is it possible, that your tank is too big for your fish?

Why yes of course.


Less fish in a bigger tank can mean that your fish are facing isolation.

Fish are social beings, and they like to stay active and interact with each other.

However, if the tank is too big, the fish will interact less and spend more time in seclusion.

That too can induce stress in your fish, and they might not be very pleased in your tank.

These conditions can also induce weight loss in your fish and deteriorate their health.

3- Your fish are not getting along with each other, could that cause death!

The compatibility of your fish amongst themselves is also important.

Most fish do have specific compatibility and are happy with the social cohesion among themselves.

However, some species have problems settling with a specific gender or other species.

Things to be sure of:

Always make sure that you ask the pet store owner questions regarding your fish.

Inquire about their compatibility and reaction with other species.

What can you do about this problem?

If you plan to add newer fish to your tank, then make sure you look upon them too! As a tank owner you should research upon the type of fish and the sex they get along with. Some fish are very aggressive and require more isolation than others

You do not want to wake up one day to find half of your fish tank dead just because of one aggressive alpha.

4- Water Conditions could be the reason why your fish are dying?

So, let’s dive into another critical factor, that is water conditions!

Water conditions if not right mean that your fish are always in a stressful environment.

This also means that your water might not have the right pH balance and could be getting dirty constantly.

One of the mistakes you might be making is not conducting regular water changes.,

Dirty water means that your fish are consuming all their waste back into their bodies.

This can seriously harm their immune systems and make them prone to more diseases.

In addition to this, it also induces a lot of stress in the fish and might spread more illnesses in your tank.

Water conditions also put a lot of pressure on the filter and if it gives out due to overburden which can also be very dangerous for your fish.

5- Mineral Imbalance contributing to your fish death

A mineral imbalance means that the water in your tank might be rich in nitrates, nitrites, ammonia, or perhaps chlorine.

It can also mean that your tank is lacking in these minerals!

You might be using regular tap water for your tank which can be deadly for your fish.

Tap water has chlorine, ammonia, and other heavy toxic compounds that make it safe for us to drink and use in our houses.


These conditions are not at all ideal for your fish!

It is necessary that you use water conditioners to stabilize the water and remove these toxic compounds.

Doing this creates a safe and healthy environment for your fish to thrive in.

Moreover, if the fish aren’t getting the right amount of nutrients, they will most likely suffer from weight loss issues.

Your fish might stop being interested in socially interacting with other fish and become unhappy overall.

The plants in your tank might not grow properly if you have a saltwater or a reef tank.

Most fish tend to enjoy plants and greenery in their tanks, but your plants may start to decay if they are not getting the right amount of nutrients!

6- Overfeeding and how it can cause your fish to die?

Overfeeding is perhaps one of the most significant contributors that affect your fish as well as the environment of your tank.

Food tends to decay over time, and that can very quickly turn into toxic waste.

This can also give rise to bacterial colonies, that are harmful to your fish.

Food then settles in the gravel, and it also makes the water murky and cloudy much faster.

Apart from this, there are other problems that your tank might experience due to overfeeding.

One of the biggest challenges is how bacteria also boosts algae outbreaks in your tank.

Excess nitrogen can promote algae growth, and it might start taking over your deck or the glass walls.

In addition to this:

Excess food waste can also increase pest snails in the corners of your decor and gravel.

Here is what you can do:

It is recommended that you only give quality flake food and blood worms in small quantities.

Try to only feed your fish what they can consume in under a few minutes.

You can also set apart a fasting day where your fish don’t consume any food at all!

This balance will make sure that there is no excess waste being produced by your fish or by extra food.

7- How common Diseases can get deadly for your fish?

Well of course diseases are also a major reason why your fish might be ending up dead in your tank, regardless of all your efforts.

The most important step is to recognize when your fish might be sick and pick up the symptoms they give off.

Sick fish may have inflamed fins, thread-like structures protruding from the gills and white spots.

Yes, it is true!

Your fish do have the natural immunity to defend themselves from illnesses,

But these diseases might get the best of those fish who are already stressed!

Stressed fish have lowered immunity, and that makes it harder for them to defend themselves from common diseases.

What kind of diseases is fish susceptible to?

There are many different diseases that, while they are common, they can very easily make your fish a target.

Especially if your fish are in a stressed environment.

Examples include parasites, white spots and other diseases that can take a toll on the health of your fish.

8- How Bad tank management might be causing your fish to die.

Bad tank management is perhaps one of the more pressing factors that can drastically change the environment of your tank.

As a tank owner, you probably are familiar with the labor that goes into maintaining a tank.

Things have to be maintained and cleaned regularly.

Some owners might think that water changes are sufficient to maintain a healthy and safe environment.

However, there is much more to maintaining water, than changing the water from time to time.

More about tank management:

Water changes do not just require you draining out the old water and pouring back the new one,

In fact, you might need to use a proper water conditioner that stabilizes the water and removes the toxic compounds from it

Other than that, most tank owners make use of water clarifiers that help clear up murky and cloudy residue.

You have to make sure that the water pH is ideal for your fish is to breed and thrive in.

Gravel and decor:

While gravel and decor might not require frequent cleaning, they can easily contribute to making the tank water dirty.

Gravel tends to store food waste and the waste produced by your fish.

It can also harbor bacteria very easily, that can lead to boosting the algae growth on the walls of your tank


You need to make sure that they are being cleaned out with every water change.

9- Appropriate Filtration affecting your fish health.

Can an improper filtration system really affect the health of your fish?

Well, the answer is yes!

If your filter refuses to work correctly due to negligence, it can very easily affect the environment of your tank

Filters are something you need to replace and maintain periodically.

If you fail to do so, then it will adversely affect the biological cycle inside your tank.

What can you do to make your filter function properly and maintain its components?

You need to periodically clean out the gunk and filth that it has been collecting over time.

Make sure you also change the carbon filter from inside as it is a vital component that helps the filter clean your water.

Your filter might also not be working because it is under-powered for the amount of water in your tank.

Another thing:

Make sure you pick the right one according to the number of gallons of water.

If you fail to maintain a proper filter, it can release more waste into the water instead of cleaning it up.

That also means that your water is retaining all the toxic bacteria and compounds.

This can also mean that your fish are stressed and are consuming all of these waste materials.

This factor can eventually cause death.

10- How the Temperature balance of your aquarium can cause death.

Temperature too can play a vital role in stressing your fish out and affecting their health.

If the water gets too hot or too cold, that might make the water unsuitable for your fish to swim in.

This can very easily change their body temperature a lower their immunity and metabolism.

This also makes your fish susceptible to more parasites and diseases

In the winter is the water tends to get too cold and can slow down your fish is metabolism which may mean that it won’t eat as much.

Try to use a water heater that can regulate the temperature throughout the seasons.

Make sure you turn off the light and also give a natural non-light period to the water as light also tends to heat the water up.

It is essential that the water temperature is regulated continuously, so your fish have an ideal environment to thrive in.

And another thing,

If you have Tropical fish, it is recommended for you to get a heater since they are more sensitive to temperature changes

A lot of the time water temperatures can change rapidly after a water change.

That means that the new water is much cooler!

If the water temperature changes rampantly, it can give your poor fish a shock!

Which is deadly for them.

So Beware!

12. Common mishaps that could be causing your fish to die.

Aquariums do require a lot of time and effort, and as humans, it is possible that we cannot always give it our 100%.

Don’t beat yourself up over the mistakes you have made with your tank!

You are only human.

Keeping pet fish and maintaining the tank is a slow and steady learning curve, it does take time to adjust.

What you can do instead:

Just Make sure that you learn from your previous mistakes and don’t repeat them again!

Many things need proper maintenance from time to time.

For example, changing the filters, adding water clarifiers, stabilizing the pH levels, or controlling the light.

You might start to worry about:

Small things like overfeeding, or an unprepared tank that can do more harm than good!

Overfeeding the fish on a daily basis can also take a toll on your fish’s health.

While a lack of preparation can lead to unstable water conditions.

All these can very easily contribute to the stress levels of your fish and make the environment unsuitable for them to thrive in.

This might affect the overall health of your fish, and that can lead to death.

It is always good to educate yourself about the requirements of the fish you plan to keep!

Ask your pet store owner or Google the breed to know what kind of environment they would find the most pleasurable.

Make sure you adapt the water’s temperature and then add your fish to it.

12- Your fish could be dying due to Old Age

You fish could merely have died of old age.

Yes, most fishes do have a relatively short lifespan.

Most Bettas live up to 4 years while a goldfish can maybe last ten years.

Old age usually means your fish has a hard time keeping up with the water changes.

It may have a harder time keeping afloat or may spend more time in isolation.

This can increase the stress levels, and at that age, fish does not handle the stress well.

This is why, if your fish is nearing its lifespan, it is likely that it may die due to a minor illness or parasite.

Its lowered immunity and metabolism make it an easy target for many preys.

Sometimes it not your fault at all! As upsetting as it is, it might be your fish’s time to go.

13- Stressed fish are prone to die quicker!

Stress is perhaps one of the biggest reasons that can contribute to the death of your fish

All the reasons above cause your fish stress in one way or the other

A stressful environment can induce multiple harmful symptoms in your fish that can need to adventure death

So, what really are the symptoms caused by stress?

A stressful situation can very easily induce weight loss in your fish.

You might think they are eating okay, yet you could be wrong!

Fish with proper diets could still be losing weight!

Moreover, stressed fish are more likely to fall victim to diseases.

Stress can lower their immunity and their defense system against many common illnesses that they would otherwise be able to defend themselves against.

There is also a sudden change in the fish’s behavior.


This behavioral change may make them more antisocial with each other and trigger territorial issues.

Naturally, fish do you have a territorial complex within them which can cause aggressiveness.

Aggressiveness in fish can lead to bullying and fighting with other fish, and that can further induce stress (that leads to death).

Apart from that, your fish may start to hide and feel uncomfortable in the general environment.

Another symptom is how your fish might be swimming on top or starts to swim a little more frantically.

Are you noticing such behaviors? Then take action immediately!

How to Provide Fish with an Ideal Environment?

Let’s look into some more tips that could help you keep the ideal environment, that you could be utilizing in your maintenance regime.

Try looking up the best water conditioners, and clarifies for your specific kind of fish and water type.

The compatibility of fish amongst themselves and the biological environment is a crucial issue it can very easily cause stress and lead to eventual death.


Research! Research! Research!

As a tank owner, you should know all your tank requirements by now.

You should know how to maintain the ideal environment and do everything right on your part.

Try to check the pH levels of the water from time to time.

If your pH level goes up or down due to specific products, you could study the factors that might be affecting the PH levels of your tank!

Some water conditioners tend to disturb the balance of the water too.

You should discontinue them immediately.

If your fish are acting panicked and distressed, maybe it is time to change up the regime a little bit!

Moreover, it is recommended that you allow your fish some breathing space and clean the tank continuously.

You might be killing the helpful bacteria which are essential for your fish to survive.

Try to cycle the tank before you had in your fish after every periodic clean!

Don’t give up on your fish. These bright and bubbly creatures are worth the effort.

If you feel like you are endangering your fish then try and learn more about them, so you can provide them with all that they might need!

If you are doing everything right then leave the process in nature’s hand.

Everything has a learning curve, and we are sure you will get the hang of this too!


All these behaviors show that your fish are stressed and that is a major reason why their health is severely impacted and can cause death.

Don’t worry!

You can prevent most of these situations from happening, so your fish lead a healthy and happy life.

Make sure that you keep in mind the daily schedule of cleaning and stabilizing the water.

Learn from your past mistakes and try not to repeat them.

Make sure there is another person at hand that can help clean up the tank in case you are not available.

Related Questions

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Do Fish Know Their Owners? A new study says, Yes, it probably can. Researchers studying archerfish found the fish can tell a familiar human face from dozens of new faces with surprising accuracy.

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