How to filter a freshwater fish tank without a filter so fish do not DIE!


The purpose of aquarium filters is to eliminate and transform organic waste from fish and aquatic plants. The main action is filtration. 

How to filter a freshwater fish tank without a filter? An aquarium without a filter would clog very quickly, water should be changed every day which would be very restrictive. With some small tweaks and setting up an easy routine, all negatives of a missing filter in your aquarium can be handled. 

The purpose of aquarium filters is to eliminate and transform organic waste from fish and aquatic plants. The main action is filtration. The filters work in conjunction with a pump that is used to create water currents and thus promote the well-being of fish. By installing a filtration system adapted to the aquarium, the user will change the water less often while offering good living conditions to his fish farming. 

Is A Filter Necessary For Fish Tank?

Freshwater ponds and lakes of the world are large enough to achieve an ecological balance. By that, we mean that they are able to reach equilibrium whereby the fish population adjusts according to conditions and fish excreta is all dealt with biologically and there is no build-up of ammonia, nitrites, and nitrates making the water poisonous to fish.

Aquariums, on the other hand, are a microcosm of the natural world and need a great deal of help to achieve any kind of equilibrium. Without external help, the water would very soon become foul and kill all the fish.

The usual reason is that the fish density found in our ponds and lakes is much less than what we like to have in our aquariums.

Even changing one-third of the water every week is not enough to keep the water safe because the resident bacteria cannot possibly deal with the amount of waste that fish in such high numbers will produce.

Consequently, a freshwater aquarium filter system is essential, although you do not necessarily need a traditional filter.

How Does No-Filter Affect My Fishtank Generally?

An aquаrіum wіth lоtѕ оf рlаntѕ and vеrу fеw fіѕh саn ѕоmеtіmеѕ ореrаtе wіthоut a fіltеr, but that is not аn іdеаl ѕіtuаtіоn. In аddіtіоn, dереndіng uроn the type оf fіѕh, your fіѕh tаnk mау not bе аffесtеd.

Sоmе fish аrе аblе to ѕurvіvе іn a bit cooler water. Hоwеvеr, thеrе are ѕоmе fish thаt аrе еxtrеmеlу ѕеnѕіtіvе tо tеmреrаturе, fоr example, angelfish аrе vеrу sensitive, they mау nоt ѕurvіvе іn a tаnk wіth a fіltеr.

Sometimes, a filter does not matter. A proper setup should not build up anything harmful that quickly. However, most types of filters do have the added benefit of increasing oxygen exchange in fish tank water. Again, that is something that under most conditions will not rapidly fluctuate if everything else is in order.

The larger your volume of water (and less surface area), the slower your tank’s heat will change. Obviously, the closer the surrounding atmosphere’s heat to your tank’s ideal temperature will reduce risk. 

How Long Can Fish Live In The Fish Tank Without A Filter?

How long your freshwater fish can live without a filter depends on the species of fish and your aquarium conditions. Some types of fish may spend their entire lifespan – in some cases, a decade or more – filterless; others do it through a single day. In addition, cleanliness, gravel, and live plants determine if some species can live without a filter.

A totally different story is to keep fish in a fishbowl, the lifespan of fish can be dramatically shortened. All aspects of fishkeeping in a fishbowl are broken down in this article. Should Fishbowl be banned? There is only one piece of advice about this, just stay away from Fishbowls.

Labyrinth fish

Labyrinth fish are named after their specialized labyrinth organs, which allow them to breathe air from the surface of the water.

Like other fish, labyrinth fish can use their gills to breathe oxygen dissolved in water, but they are not so dependent.

Although most do not have to breathe some of their oxygen from the water, they can live with much lower levels of dissolved oxygen than most other fish. Labyrinth fish include gouramis and bettas, or fighters.


Like labyrinth fish, goldfish can supplement the air they breathe through their gills by breathing in the air from the surface.

They are currently not ranked with labyrinth fish, and the jury is still out on whether their labyrinth organs have a respiratory function.

In any case, the effect is the same: if they need dissolved oxygen, they do not rely completely on upon, and they can live in ponds and tanks that lack filters.

Other fish with the ability to survive without a filter in the tank

How long other fish can live without a filter depends on the amount of dissolved oxygen in the water, the specific oxygen requirements of the species, and the size of the fish.

Some species can survive indefinitely if your tank is heavily planted since plants add oxygen to the water.

The rule of thumb is that fish that live in ponds in the wild can survive without a filter, while fish from streams and rivers cannot because they need a current to generate enough oxygen.

All non-air breathers will die in an unplanted tank as soon as available oxygen is used. This usually happens in a few hours.

What Fish Do Not Need A Filter?

There are a few species of freshwater fish that do not require a filter in a tank. These include:

  1. Betta fish: Betta fish, also known as Siamese fighting fish, are a popular choice for small tanks because they are relatively low maintenance and do not require a filter. Betta fish are highly adaptable and can tolerate a wide range of water conditions, including low oxygen levels and a lack of filtration. However, it is still important to maintain a clean and healthy environment for betta fish, including performing regular water changes and avoiding overfeeding.
  2. Goldfish: Goldfish are another type of fish that do not require a filter in a tank. Goldfish are known for their ability to tolerate poor water quality and can survive in a tank without a filter as long as the water is regularly changed and the tank is kept clean. However, it is important to note that goldfish can produce a lot of waste and can be sensitive to changes in water quality, so it is still important to provide proper care and maintenance.
  3. Otocinclus catfish: Otocinclus catfish, also known as oto cats or ottos, is a type of small, peaceful fish that do not require a filter in a tank. Otos are natural algae eaters and can help to keep the tank clean by consuming excess algae and organic matter. However, it is important to provide a suitable environment for oto cats, including proper lighting and substrate, and to avoid overcrowding.
  4. White clouds: Called thus by the mountain range of China, where a young person discovered the species, the cloud white fish are of silver or brown color. Because the white minnow mountain mesophyll reaches only 1 to 1 1/2 inches long, the fish can live in a small fish tank without filters. White clouds require only one or two gallons of water for the fish to live healthily.

It is important to note that while these fish may not require a filter in a tank, it is still important to provide proper care and maintenance to ensure their health and well-being.

This may include performing regular water changes, using a water conditioner to remove toxins or harmful chemicals, and monitoring the water quality to ensure it is within the optimal range for your specific fish species.

What About Plants And Missing Filter In The Fish Tank?

Plants offer many benefits to the environment of an aquarium. Among other things, they provide fish and invertebrates with a natural refuge where they feel safe.

During their growth, plants generate oxygen through a process called “photosynthesis”.

Plants turn light and carbon dioxide into oxygen, which is essential for any living organism in an aquarium, including beneficial filtering bacteria. High levels of oxygen contribute to active fish that are resistant to disease.

The planted aquarium does need extra help with biological filtration, regardless of the fact that aqua plants take in nitrogen on their own.

To do the filtration as you would expect, the plants’ well-being is important, and they need sufficient light per day too.

In addition, the plants serve as lungs and kidneys in the aquarium, during the process of photosynthesis; they consume the carbon dioxide present in the aquarium and reject co2 necessary for the survival of the fish.

They also consume the nutrient waste released by the fish as well as the nitrate and phosphate present in the aquarium, which makes it possible to limit the presence of algae.

Another advantage is that the roots of the plants oxygenate the substrate in which they are planted: this avoids the formation and recovery of the aquarium’s toxic gases that are often formed in an anaerobic environment.

What Fish Do Not Need An Air Pump?

At the time having a fish tank, you can come to think that many expenses are required, one of them being the pump that gives artificial oxygen to the fish, something that is indispensable.

Oh well, that is what was believed. And it is that in fact there are several types of fish that do not need artificial oxygen to be able to live, for that reason they can be in a fish tank without this product. Noting that, a bowl is also an excellent choice to have them.

Here Are Five Fish That Do Not Need Artificial Oxygen To Live Happy In The Aquarium

  • Guppy fish – Being really small but really precious, these fish do not need oxygen for their existence, due to their size they can be kept in a bowl. It should be noted that these fish are reproduced quickly and in large quantities, so if you have a partner, you should not miss if you have dozens from one day to the next, something that looks even better in the fish tank.
  • Betta fish – Being one of the most beautiful fish in the world, they are usually solitary, so it is good to have them in a small fish tank individually. Its colors are unique and eye-catching, it is an alternative that cannot be missed.
  • Fish Colisas – These little friends can also live without oxygen. Its shape is oval and its colors a charm.
  • Fish Guramis – The fish guramis have a shape similar to the fish slides, but small details make them different. It should be noted that its colors are one of the things that I most like, especially if it is a blue Guramis.
  • Lungfish – This is a bit more extreme, but it’s all a matter of taste. They are large, and their shape is like that of a snake, they can also live without artificial oxygen.

Is It Possible To Have A Clean Aquarium Without A Proper Filter?

Of course, it is possible to have a clean aquarium without a filter. However, it requires more work down the road. You need some supplies to clean your aquarium without a filter, which we are going to talk about in the next paragraph.

How To Keep The Fish Tank Clean Without A Filter And Changing The Water So Often?

It is possible to keep your fish tank clean without a filter and change the water frequently. It is definitely possible with the use of the following supplies. All listed below.

  • Siphon
  • Towel
  • Algae Pad
  • 2 fishnets
  • Clean cloth
  • New toothbrush
  • Gravel vacuum – cheapest one on gravel cleaner for Fish tanks
  • Water conditioner 
  • 2 large buckets (5-10 gallons)
  • A temporary fish tank or container – an affordable small temporarily fish tank (Amazon) option
  • Freshwater in the quantity you want to replace
  • Aquarium-safe glass cleaner or a vinegar-based solution.

With the use of the aforementioned supplies, you can clean your aquarium by:

  1. Scrubbing the sides of the tank
  2. Filling your temporary fish tank or container with some original fish tank water
  3. Removing fish or aquatic creatures from your tank with a fishnet
  4. Removing decorative items (plants, rocks, etc.)
  5. Setting up your five to the ten-gallon bucket
  6. Siphoning out the old water
  7. Vacuuming debris from gravel
  8. And finally, cleaning the exterior of the tank.

Thereafter, it is a must to reintroduce tank components, and to do so; you need to:

  1. Return decorations when you are done cleaning your tank
  2. Treat water with a conditioner that neutralizes chemicals like chlorine, chloramines, ammonia and so on.
  3. Replace the removed water with fresh, treated water
  4. And as a final point, get the fish accustomed to the new environment.

Shouldn’t you find these extra steps a little overwhelming, feel free to set up your aquarium with no filter.

You can definitely choose from fish species and plants that can easily not only survive but live happily in not filtered fish tanks.

On another hand, this obstacle can bring your love for your hobby/tank to the next level. Time spent caring for your fish will pay back through the bond that you will build with your pet fish. Happy Fishkeeping, Cheers.

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