Fish Tank Filter Not Working-How to Save My Fish?

I have seen my fish dying due to the improper working of filters two years before when I was not experienced in this field.

Last Sunday, one of my friends’ fish died due to this reason. And, I again found it pathetic like my previous experience that happened due to my ignorance.

Then, I thought I should provide some tips according to my knowledge to hobbyists, especially beginners who make mistakes in filter operation.

Will Fish Die Without a Filter in the Tank?

Yeah! Not instantly, but your fish will die earlier than their normal living period if you keep them without a filter inside the aquarium. 

As I experienced for a long time, fish are sensitive to their atmosphere and the water quality. In this case, as a hobbyist, you know that the water quality can’t be maintained without a filter. 

Hence, I hope it’s clear to you that, you can’t save your fish for a long time if you don’t set up a filter in the aquarium or if the filter doesn’t work properly. 

Why Do Fish Die Without Filter?

1. Toxin Build-up

Following the previous fact, I think I should make the points clear about what’s the reason behind the fish’s death. Here, the first point that I caught was the toxin build-up.

Whenever the filter is not working properly, the toxic materials produced through different reactions can’t be removed from the filter.

As a result, the fish take up those toxic materials with their food and breathing process. Thus, they become sick and can’t live for a long time.

2. Degradation of Water Quality 

Already, I have mentioned that fish are sensitive to their water quality. Their growth, development, breeding, and overall living processes completely depend on the water quality. 

Suppose, you are in a healthy environment, you can take fresh air and other materials. As a result, you will get a healthy and long life.

In the same way, fish also need such an environment. But, when the filter can’t purify the materials or components of the water, the water quality degrades day by day.

For example, the water may become heavy or may contain different toxic elements as the first one. Thus, the water becomes unsuitable for the fish living.

3. Debris Accumulation 

Let’s turn to the third point which contains the debris accumulation. It’s a normal issue that fish create excreta after having their food. 

Other types of materials, like dust or dirt, also may accumulate in the filter water. Whenever you are setting a filter, these materials are going for purification at a certain interval. 

Contradictorily, in the absence of a filter, this debris remains inside the filter and they store up quickly which creates an unhealthy situation for the fish and leads them to death.

4. Algae Growth 

Don’t you think algal growth is a common issue for the aquarium? Algae may grow quickly in the aquarium if you don’t take enough initiative for them.

Without a filter, you can’t complete this procedure. Also, to remove algae, you may require an algae scrubber or such types of materials. 

But these things also need to be purified. Otherwise, they become problematic for the fish inhabitants. Hence, you can’t continue without a filter in this case.

5. Absence of Aeration and Oxygenation

All the problems that I have explained in the previous 4 points end in one severe problem together and that is the absence of oxygenation. 

You may know about DO which is dissolved oxygen in the water. Whenever the dirt accumulates in the water, the amount of dissolved oxygen reduces.

Such a reduction of oxygen is harmful for the fish as they can’t breathe properly and the lack of oxygen creates different diseases for them.  

As a result, the water quality along with low oxygen levels hampers their lifestyle badly. Soon, they die due to different diseases.

Why Do Aquarium Filters Stop Working?

1.No Suction 

As you know, filters are important for your fish, so you should have a clear idea of the filter activities. Following that, I think it’s important for all hobbyists to know the causes that make the filter stop working. 

Well, this can be of different types. One thing may happen: the filter is not able to complete its suction process properly. 

No suction problem can happen due to varied reasons. For example, if debris is stuck in the tube mouth, the suction process will be hampered. 

Besides, the presence of air bubbles can also create mismanagement in suction. In this case, the suction will also be stopped.

2. Broken Parts

Your filter may also stop working due to broken parts. Suppose, a part of your air conditioner is not broken or destroyed. Will it work?

No, right? In the same way, any broken part like the impeller, hose, pipe or other materials of the filter will also destroy the filter activities. 

Nevertheless, if you don’t change the broken parts of your filter, it won’t work and within time, it will become a junk part for your aquarium. 

3. Gathering of Dirt

I have already said that dirt can be gathered in your aquarium which is hampering your fish. But the same thing may also happen inside the filter.

In the case of improper working, dirt from the water accumulates in the filter pipe. After some time, this dirt becomes clogged in the filter and gradually stops working completely. 

Let me mention one more thing. Dirt accumulation can occur at any place of the filter. But whenever it is clogged in the pipe, that hampers the filter activities fast.

4. Imbalanced Flow Rate

I have experienced several types of filters in my aquariums. That’s why I know that every filter has a balanced flow rate and you have to adjust your water level in that specific position. 

If the water position is too low, the filter won’t work properly and that is common. On the other hand, if you try to flow more water than its capacity, it will become a burden for you.

In that case, the filter won’t work at a balanced rate and this imbalanced situation will create a harmful position for the filter and it will stop working. 

5. Completely Destroyed

The last point is the filter can be destroyed. Every material has a deadline which means you can use an electronic device for a definite period.

If you are keeping a filter for a long time, it will lack its capacity though you try to keep it working by providing all types of care.

Hence, you have to change your filter after a certain time which depends on your filter type, tank type, and the water quality. 

How Can I Understand My Fish Tank Filter Isn’t Working? 

If you are enough experienced or a tricky person, you will be able to grab this answer from my upper description. Whatever, let me make this option clear to you.

If your filter stops working, you will find some symptoms in your filter. Like-

  • Algae growth will be extremely enriched. 
  • You will find dirt accumulated in different parts of the filter. 
  • Your fish will become sick and different viral attack or bacterial attack symptoms will be clear in their body.
  • You will find your fish are lacking oxygen and are not able to breathe properly. 
  • If you test different elements of the filter, they will be excessive than their optimum range.
  • The result of the water quality test will not be satisfying for your fish.

As your filter is not working, the maintenance of water quality or other materials will be difficult. At that point, you will find these symptoms in your aquarium. 

How to Save the Fish From Dying?

Till now, I have only been discussing the problems. Shouldn’t I provide their solutions now so that you don’t need to search for them in other places where the fish problems are occurring due to the filter issues? You have to identify the problem first. You need to find out if the filter is destroyed or if it is facing difficulty in purifying water.

If you find any problem related to the filter that I mentioned before, you should sort out that. For example, if debris accumulates there, clean it with a brush after soaking it for 30 minutes in warm water.

If any of the parts of the filter is broken, change it fast. If you want to get a detailed solution about this fact, you can search for other articles on my website where I have explained it elaborately (Link: Fish Tank Filter Running Slow-How to Fix).

But, if the filter is not working despite you having tried all the tricks, it’s time to change it. In that case, change the filter and install a new one in its place. Thus, you can save your fish from dying early. 

How Long Can a Fish Live Without Filter?

This is the most common question that I face when I talk about this matter with my friends or neighbors.

Look, fish are helpless without a filter inside the aquarium. According to the water quality and fish species, a fish can live for 3 to 7 days without a filter. 

Hence, if you are conscious about your fish, don’t waste time. Install a filter or repair it as fast as it needs. Otherwise, the fish community of your aquarium will be destroyed. 


How often should I clean my filter?

It depends on the filter size, filter type, tank size, and water quality of your aquarium. I often suggest a monthly check but if needed you can do it more frequently.  

What can I do while repairing the filter?

You can use a backup filter for temporary relief while fixing the main filter. Otherwise, you can conduct a partial water change with dechlorinated water as a backup program. 

Final Words

Okay! I have reached the last part of my discussion. There is nothing more to say, but I only want to suggest checking your aquarium condition, fish health, and filter activities regularly. 

If you do so, any problem will not become so severe that it may lead your fish to die. But if you spend lazy time or remain so busy with your work that you can’t make time for them, the aquarium is not for you.

Regular and technical maintenance can save your fish from dying as it helps to keep them far from any type of difficulties related to the filter.

Howard Parker

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