What caused my betta fish to die so suddenly?

In this article, we will answer the question “What caused my betta fish to die so suddenly?”. We will also discuss the most common causes and discuss how to prevent them.

What caused my betta fish to die so suddenly??

While you may believe your betta died abruptly, they could have been dying for some time without your knowledge. Several factors might cause your betta fish to die, the most prevalent of which are:

1.   Lack of acclimation;

2.   Overfeeding;

3.   Absence of a heater or filter;

4.   A shock from water changes;

5.   Wrong tank setting;

6.   Poor water conditions;

7.   Overcrowding;

8.   Inappropriate tank size;

9.   Poor diet;

10.   Issues beyond your control.

Lack of acclimation

Another typical blunder is failing to acclimate their betta. If you don’t allow your betta enough time to adjust to its new tank’s pH and temperature, the resulting shock to its system can be fatal. 

To acclimate your betta, open the bag in which it was delivered and float it in water. After it has been floating for around 10-15 minutes, you should add some of your water to it. Repetition of this procedure every 10 minutes for 45 to an hour is required. 

The additional time will let your betta to become used to the new settings and prevent it from being unwell as a consequence of them.


Even if your betta appears to be constantly hungry, they can be overfed. Unfortunately, they will eat until they are completely satisfied. Your betta may become constipated or develop swim bladder illness as a result of this. 

You may believe that your betta will not die unexpectedly and that you would have seen the warning symptoms. Any food that isn’t consumed will decompose in the tank, generating an ammonia build-up that could lead to ammonia poisoning and death. Ammonia poisoning can strike quickly, killing your betta in a matter of hours. 

For those of you who are asking how much you should feed your betta, the answer is that you must feed it twice a day for no over than 2 minutes on each occasion. Keep in mind that its stomach isn’t much bigger than its eye.

Absence of a heater or a filter

One of the most popular misunderstandings is that bettas, like goldfish, do not require a tank warmer. As it turns out, this is not true in the great majority of instances. 

Bettas are tropical fish that must be kept at a temperature between 76 and 82 degrees Fahrenheit to live. It is probable that the temperature in your betta’s aquarium will fluctuate and even dip below 76°F if you do not have a heater in place.

Temperature shock is common as a result of fluctuations and unexpected reductions in temperature, and it can be lethal quickly. 

Even if you think your house is usually warm enough, one temperature change outside the tank might radically modify the temperature inside. This is especially true with tiny tanks. 

If you have a betta tank but no heater, you should get one as soon as possible. The best warmers for 5-gallon tanks are listed below. 

Another popular misunderstanding is that bettas don’t require a filter as well. There is some truth to this. You can avoid using a filter if you make 100 per cent water changes regularly. However, this would still put a lot of strain on your betta. 

Bettas require filters to purify their tank’s water, making it more welcoming and removing any ammonia. 

A lack of filtration might cause the water to become poisonous due to ammonia, culminating in ammonia intoxication once more. If you don’t have a filter and your betta died quickly, it’s possible that ammonia poisoning was the cause of his death.

A shock from water changes

When it comes to 100% water changes, they might also cause your betta to die unexpectedly. Your betta will need to acclimate whenever you conduct a 100 per cent water change, just like when you introduce a new betta to your tank. 

The difficulty is that there’s no way to get your betta to acclimate when you change the water. This is true unless you constantly place it in a bag of old tank water before using it. 

Regardless of the method, your betta will be stressed out by the constant change of water. That is why having a filter and performing partial water changes is much preferable.

Wrong tank settings

Are you checking your tank’s pH? Have you studied up on the requirements for your betta’s survival? 

Unfortunately, the idea that bettas can survive in almost any environment is simply not true. To survive, your betta requires a pH level as near to 7 as possible, as well as plenty of hiding spots. 

You run the risk of your betta dying if you don’t put up an aquarium for it. Particularly if the pH is abnormally high or low. If either of these things happens, the water will begin to burn your betta until it dies. 

If you don’t already have a test kit, you should obtain one as soon as possible. The API Master Test Kit is a fantastic option to consider. The pH level, as well as the presence of ammonia, nitrites, and nitrates will be tested, and the results will be shown.

Poor water conditions

You already know that a filter will be required in your betta’s tank, but even with one, the water conditions can deteriorate. 

Increasing the amount of food you feed your fish and the number of fish in your tank may quickly degrade the water quality in your tank.

While bettas can survive in inadequate water for a short period, their longevity will be dramatically reduced. In certain situations, if things become severe enough, your betta will succumb to ammonia toxicity and die shortly. 

It’s also a good option to vacuum the sediment in your aquarium to eliminate any decaying material that has accumulated at the bottom.


An overstocked tank will not only result in poor water quality. It can play a role in your betta’s death in several ways. 

To begin with, certain bettas have a disposition that necessitates their isolation. They’ll attack and be violent towards any other tank members. This will not only stress out your other fish in the tank, but it will also stress out your betta. 

For the second time, an overloaded tank will give your betta limited swimming room to move around. This is going to stress it out, and it may die abruptly as a result of it. 

Another issue is that your betta will struggle to breathe. Bettas, thanks to their labyrinth organ, can breathe from the surface. They do, however, take in water through their lungs as well.

When a tank becomes too crowded, there isn’t enough oxygen to go around. This could not only kill other fish, but it will also stress your betta.

Inappropriate tank size

If you look up what size tank a betta should be in on the internet, you’ll find a lot of conflicting and potentially deadly information. Some say 2.5 gallons, others say 5 gallons, while yet others suggest 1 gallon. 

The truth is that if you don’t want your betta to die quickly, you should put it in a tank with at least 5 gallons of water. Bigger, on the other hand, is usually better. 

A tank that is too tiny will annoy your betta, stress it out, and maybe make it melancholy. (Yes, bettas can suffer from depression.) When any of these things occur, your betta is more likely to die suddenly. 

On top of that, because the tank is tinier, the likelihood of experiencing fluctuations increases, and the severity of such fluctuations increases. It may seem contradictory, but the larger the tank, the easier to maintain it becomes. Things take a lot longer to go wrong because there’s more water. 

If you had your betta in a tank that was less than 5 gallons, you should get a bigger tank before getting another one.

Poor diet

Overfeeding it’s not the only factor that might cause your betta’s death, though. In general, a poor diet can quickly lead to death. Bettas eat meat and are primarily carnivorous. Even if you see them consuming plant matter, they aren’t getting the nutrition they require. 

Feed your betta a variety of foods, including live food, frozen food, freeze-dried food, and high-quality pellets. Bettas love daphnia as a food source. Brine shrimp and mosquito larvae, on the other hand, are excellent alternatives. If you want to feed them bloodworms every now and then, go ahead, but don’t go overboard with it.

Also, don’t believe that bettas can survive just by consuming plant roots. This is a deception, and while it may appear appealing, your betta will suffer greatly as a result. 

Uncontrollable problems 

Betta fish are mass-produced in large quantities. They spend a significant portion of their existence in little containers until you take them home. Even if I state that a tank with less than 5 gallons of capacity pollutes fast, you can picture how nasty those small cups must be. There is a sense that the deck is set against these unhappy fish right from the beginning. 

It is impossible to tell whether your fish is sick until you bring it home from the store. You have no idea of verifying whether it has a congenital condition that will cause it to die despite what you do to save it from death. While you may take a new pet to the veterinarian to be examined for such issues, you won’t be able to tell with a little fish. 

It is important not to be too harsh on yourself if you believe you have done everything correctly but your fish still dies. Yes, it’s always a good idea to examine your fish-keeping techniques and see if there’s anything you might have done differently. But bear in mind that it’s possible that you’re not to blame at all.

Similarly, if you’ve done everything wrong and your betta has lived for years, don’t think that doing the proper thing won’t make a difference. Some fish, like people, can live unhealthy lives and nonetheless live to be elderly. And some people can live in clean, heated, safe, and joyful water and still die young.


Bettas are known to die from natural causes. Keepers should not be neglected. It is possible to avoid dead Betta fish in your tank by learning suitable environmental conditions and monitoring them using test kits. Stress reduction and early disease treatment are also beneficial.


In this article, we answered the question “What caused my betta fish to die so suddenly?”. We also discussed the most common causes and discuss how to prevent the sudden death of your betta fish.

If you have any thoughts or doubts, feel free to drop us a comment below!

Frequently Asked Questions (FAQs): What caused my betta fish to die so suddenly?

What is the most effective method of keeping my betta fish alive for the longest period of time?

You can lengthen and increase the quality of your betta’s life by regulating its habitat and ensuring it has all it requires. 

Can a betta tank ever have too many decorations? 

Yes, there is a risk of overdoing it. When it comes to designing your tank, create a balance between objects that appeal to you and those that satisfy your fish’s demands. 

Do Bettas pretend to be dead? 

Betta fish do pretend to be dead. Betta fish prefer to sleep in postures that make them appear to be dead, such as on their backs. When you notice your betta fish floating upside down, don’t be alarmed; it’s most likely asleep. 

What is the best way to know whether my betta fish is in pain? 

A healthy betta fish is constantly flaring its fins and gills, as well as fluttering around in the water. Once it becomes ill, it becomes less vigorous and may even have its fins restricted, causing it to lose its swimming ability. You may have noticed that when they are in excruciating agony, they hardly move and are frequently found at the aquarium’s bottom. 

What can cause a betta fish’s death? 

A poor habitat, such as unclean water, unsuitable fish, a tank that is too small, and other factors, is the most prevalent cause of mortality in Betta fish. Betta fish are prone to stress, so it’s crucial to limit their exposure to it and keep an eye on how they react to new situations. 

What is the average life expectancy of a betta fish? 

Betta fish have a lifespan of 2-4 years on average. The environment in which you maintain your betta fish has a direct influence on the length of time they live. By maintaining their aquarium clean and monitoring their diet, you may be able to help them live a lot longer.


Why Did My Betta Fish Die Suddenly? (17 Common Reasons!). https://www.bettacarefishguide.com/why-did-my-betta-fish-die-suddenly/

Dockett, E. 2021. Top 6 Reasons Betta Fish Die and How to Prevent It. https://pethelpful.com/fish-aquariums/Reasons-Betta-Fish-Die

Why Did My Betta fish Die Suddenly? Top Factors Leading to a Dead Betta. https://japanesefightingfish.org/dead-betta-fish/

Why Did My Betta Fish Die Suddenly? https://bettafishworld.com/why-did-my-betta-fish-die-suddenly/