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How much oxygen is in the aquarium

maintenance, care, compatibility

On the question of whether oxygen is needed in an aquarium, the answer is simple – we need it. However, some people perceive the advice of water aeration experts as a guide to action and start planting heavily. aquarium plants and use several compressors at once.

They do not know that it is harmful for fish and may cause gas embolism. In this case, air bubbles appear in the blood of fish, which can lead to death. Therefore, the saturation of water in the aquarium with oxygen should be carried out according to the rules:

  • change water in small portions;
  • choose the right composition of fish;
  • keep track of the number of plants;
  • regulate the air flow from the compressor.

In this case, the perfect balance of oxygen will be achieved and your fish will not suffer.

Aquarium Aquarium: Methods and Methods of Enriching Aquarium Water with Oxygen

Everyone knows that equipment for aeration of aquarium water is paramount and vital.

However, many beginners and even already experienced aquarists do not know how it works, they do not fully understand why it is needed and what happens in an aquarium with a lack or excess of oxygen.

In this article, I would like to try in a simple narrative manner to lift the veil of aquarium aeration secrets, to bring excerpts from the already written material of Runet, and also to tell about some of the “secrets” of O2 supply to the aquarium.

I think I should start with a short story about mechanical aeration, by which I mean the process of mixing air with aquarium water using aquarium equipment (pumps and compressors).

The principles of operation of such equipment are well known and understood by everyone, so I will not focus on them. It is more interesting to tell about two misconceptions of newcomers of the aquarium craft, connected with the aeration of the aquarium water by mechanical means:

1. Usually everyone thinks that the enrichment of water with air occurs through bubbles, which the compressor will drive into the water. However, it is not!

Mixing air with water occurs on the surface of the water. The aerator creates vortices and vibrations from bubbles on the water surface, as a result of which mixing occurs.

We can say that the saturation of aquarium water with air (oxygen) is not due to the bulbushes, as such, but from their intensity and water flow, which improves the absorption of oxygen from atmospheric air.

2. The second important nuance of mechanical aeration is its continuous operation. A big mistake for beginners is to turn off aeration for the night, so that it does not rustle.

Such an action can lead to fatal consequences, because overnight asphyxiation will “earn” not only fish, but also all hydrobionts, up to nitrifying bacteria, which leads to a disturbance of biobalance and, as a result, a “dead bog” is obtained from the aquarium, which is infested with disease-causing bacteria and live algae!

With that said, it should be noted that you should not save money when choosing and buying equipment for aeration of the aquarium, it must be of good quality and sufficient power. It is desirable that it had various nozzles and created a good “purge”.

A huge role in the “aeration of the aquarium” is played by live aquarium plants. Aquarium plants are perhaps the only natural source of “pure” oxygen – O2, which is released during photosynthesis.

The presence of abundant vegetation in an aquarium will have a favorable effect on its climate and, in particular, on the concentration of oxygen in the water. However, the plants are not a stable and unconditional supplier of oxygen to the aquarium. It is worth saying that the process of photosynthesis, in which plants emit oxygen is possible only if there is sufficient illumination and the necessary amount of CO2 (carbon dioxide).

As soon as the light in the aquarium turns off, the process of photosynthesis stops and the opposite happens – the plants begin to consume oxygen.

From the above, we can draw two conclusions:

– aquarium plants are not replaceable helpers “oxygen supply in the aquarium.” I generally keep quiet about their use in setting up the biobalance and their participation in the fight against NO2NO3.

– Alas, aquarium plants are not a panacea. Many people are mistaken in thinking that plants need only carbon dioxide, no!

They also “breathe” and oxygen is vital for them at night.

Well, now, before disclosing “aquarium-oxygen secrets,” let’s determine

Measure the concentration of O2 in the aquarium, you can with the help of tests that are sold in many aqua stores

Speaking about the concentration of oxygen, it is necessary to make a small reservation about overdose.

There are various opinions on this issue. Some, in the old-fashioned way, say that oversaturation of water with oxygen is dangerous.

Other, more progressive comrades, on the contrary, say that the abundance of oxygen favorably affects the life of the aquarium. The arguments of both are interesting, but are a separate topic for conversation.

I personally tend to think that a lot of “oxygen does not exist” (conditionally, of course). Oxygen is poorly soluble in water, it is ten times worse absorbed than carbon dioxide. Therefore, in order to achieve an overabundance of O2 concentration, it is necessary to make a lot of effort, moreover, you need to be blind not to notice an overdose.

Yes, the pH may drop sharply from an excess of oxygen, they say that colonies of beneficial bacteria are dying from its excess … but this is such a rare situation that 99% of aquarists have never even thought about it.

And now, the promised tricks and secrets of aquarium aeration

Secret number 1: Many people know that oxygen consumption by hydrobionts increases with increasing temperature, since the respiratory process increases with increasing temperature. On the other hand, the concentration of oxygen in water is highly dependent on temperature.

At a temperature of 20 ° С it reaches about 9.4 mg / l, at 25 ° С – 8.6 mg / l and at 30 ° С – 8.0 mg / l.

This statement can be perfectly used in cases of fish asphyxia. In addition, this statement disciplines beginners who think that plus or minus degrees does not matter.

Secret number 2: Perhaps the most valuable advice. Few people know about the benefits of using HYDROGEN PEROXIDE in an aquarium, this is what it does:

1. Revives choked and suffocated fish;

2. Fights against undesirable living creatures in the aquarium (hydra, planarians);

3. Fights against external protozoa and parasites;

4. Effective with bacterial infections on the body of the fish and its fins;

5. Fights against blue-green algae in an aquarium;

6. Fights algae on plants;

A well-known and respected Petersburg aquarist V.Kovalev on the Living Water website tells very well about the benefits of hydrogen peroxide:

Hydrogen peroxide – This is an environmentally friendly product. In water, it breaks down into water and oxygen – harmless substances. Therefore, if it is used correctly, then the useful microflora in the filter and the soil can be saved completely, or only slightly podzadushit (too much oxygen is released in the overdose and in the filter, which is not good for bacteria).

But the microflora will quickly recover, because no harmful substances have entered the water. Fish with proper dosing peroxide does not poison. If when applying peroxide on the sponge filters, the walls of the aquarium, fish and plants bubbles appear, then the dose was great.

Only barely noticeable bubbles on mechanical filters are permissible.

Pharmaceutical 3% peroxide is used for:


Addition to 40 ml on 100 l. When they begin to pour bubbles on the glasses, filters and, possibly, small fish, the water should be changed, the blow-down should be strengthened. If there is no effect in 15 minutes of exposure, then no longer fate … For resuscitation of fish affected by high doses of carbon dioxide, 25 ml per 100 l is usually sufficient.


Concentration to 40 ml in 100 l. It is necessary to make a few days in a row before a complete victory over the enemy. At the same time, plants can be frozen, but if lower concentrations are applied, then it is not possible to win, although the plants will be alive. However, as a rule, everything turns out, the process takes a week or more.

Anubias-type peristicular plants are relatively resistant to peroxide.


If your aquarium has your favorite plants, then you cannot exceed dosage 25 ml per 100 liters once a day. Fish usually tolerate dose without harm 30 or even 40 ml per 100 l.

The effect of daily application is noticeable on the third day. For a week, everything passes. The dose that you can still fight algae is 20 ml per 100 l.

Long-stemmed plants with feathery leaves do not tolerate peroxide, so this dosage should not be exceeded. Stylist plants can be redeemed several times in a separately prepared peroxide solution 50-40 ml per 100 liters. Hold for half an hour, an hour.

I do not know the exact time. They say that the fouling flip flops can be reduced. It is possible that peroxide will help in the fight against Vietnamese in the aquarium (20-25 ml per 100 l).

But in this case it is still necessary to reduce the nitrate and phosphate contamination of water.


25 ml per 100 l daily or 2 times a day multiple times (7-14 days).
You can prepare a therapeutic solution of peroxide from the industrial product of perhydrol – about 30% of prekis. That is, it must be diluted 10 times to get an analogue of pharmacy peroxide.

The substance is caustic and explosive! It is possible to dilute only with water in a plastic container.

Contact with metal, alkalis, organic solvents should not.

Thus, taking into account the topic of the article, it should be said that hydrogen peroxide is “unique” and plays a crucial role! With its help you can instantly enrich the aquarium water with oxygen and thus save the fish, even in the severe stage of asphyxiation.

SECRET number 3: Many people know what oxygen pills are and many often use them when transporting fish. However, few people know and come across such aquarium equipment as OXIDATORS.

Oxidators are different: for the long transportation of fish, for mini aquariums, for large aquariums, for ponds. Their essence is simple – hydrogen peroxide is placed in the vessel to which the catalyst is added, after the reaction begins, as a result of which oxygen is released.

Video how oxidizers work for aquarium

Below is a line of oxidizers, which will reveal the whole point. OXIDATOR A

Dimensions: diameter 9 cm, height 18 cm

Container Content: for aquariums up to 400 l. – 250 ml of 3% hydrogen peroxide solution, for 600 l – 250 ml of 6% solution.

Duration of work: at a temperature of 25 ° C from two to eight weeks, depending on the concentration of the solution and the number of used catalysts.

The absence of bubbles coming from the device indicates the need for recharge of the OXIDATOR.

1 liter of peroxide is enough for 1 month for 20 large fish.

You can also use it in a larger aquarium, but the duration of the instrument is reduced.

If your aquarium has a capacity of up to 400 liters and the two-week OXIDATOR operation time is too small for you (for example, you are going on vacation), you can use two OXIDATORS A by placing one catalyst in their containers. As a result, the duration of their work before recharging will increase to four weeks.


Dimensions: diameter 4 cm, height 6 cm

Container contents: – 20 ml of hydrogen peroxide solution.

Includes two 50 ml bottles with 4.9% hydrogen peroxide solution.

Duration of work: at a temperature of 25 ° C 2 – 4 weeks depending on the number of catalysts and the volume of the aquarium.

You can install up to four MINI OXIDATORS in an aquarium, or replace its catalysts with more powerful ones (from W, D or A OXIDATORS).

MINI OXIDATOR – DOESN’T REPLACE the compressor or filter, it is a universal oxidizer and works in the absence of electricity, long-term transportation of fish, increased demands on the oxygen content of the fish or summer increase in water temperature. Kills harmful bacteria and treats outdoor fish diseases.


Dimensions: diameter 8.5 cm, height 8.5 cm

Container Content: for aquariums from 60 to 150l. – 125 ml of 3-6% solution of hydrogen peroxide.

Duration of work: at a temperature of 25 ° C, 1 liter of peroxide is enough for 2 months of work in an aquarium with 10 large fish.


The first safe and self-regulating device that can be year-round supply ponds with oxygen without the use of hoses and electrical wires, even in a fierce winter.

It is designed for garden ponds, as well as large aquariums in excess of 700 liters.

Dimensions: diameter 15 cm, height 18 cm

Container contents: 1 liter of 6-30% hydrogen peroxide solution.

In the summer with a single refueling – 1-2 months.

In winter, under ice – for 4 months.

The annual need for a solution, depending on the temperature, is 3-5 liters.


Floats in the shipping container due to the ring float.

The device allows you to transport or contain a large number of fish (up to 25 goldfish with a body length of 8 cm in 20 liters of water) in a small container (can, thermo bag, bag, etc.) with a volume of 2-20 liters for a long time without an additional compressor or filling the bag with oxygen.

Duration of work – from 144 hours (at 9 ° C) to 36 hours (at 25 ° C).


The FTC OXIDATOR compact device allows you to transport or contain fish in a small container (bucket, plastic bag, etc.) volume of 2-20 liters for a long time without an additional compressor.

Increased oxygen consumption by fish with increasing temperature (within reasonable limits) is automatically compensated by the device.

One OXIDATOR FTc contains 1000 mg of pure oxygen.

The working time at a temperature of 20 ° C is approximately 12 hours. As the temperature rises, the operation time decreases, but the amount of oxygen released increases.

When the temperature decreases, the duration of work increases.

It is worth noting that oxidizers are very rarely used by aquaquimists in the post-Soviet space. They cost relatively not expensive – OXIDATOR A costs about $ 100, plus they save energy … but alas, there is not even anyone to ask anyone about the practice.

Most often they are used only for long shipments of fish.


Aeration, enrichment of aquarium with oxygen interesting video

First of all, a surplus of2 no less harmful than a disadvantage. It can cause gas embolism in fish when air bubbles appear in their blood. As a result, the fish may die.

Fortunately, such a phenomenon is rare. Nevertheless, you should not be zealous with aeration (for example, it is not necessary to install several compressors).

Please note that the rate of oxygen concentration is 5 mg / l and a little more. Measurements can be performed using special tests purchased at a pet store.

Changing water in small portions, controlling the composition of fish and the number of plants, regulating the flow of air from the compressor will help to achieve the perfect balance.

Factors affecting the oxygen content in water

What should be the dose of oxygen in the aquarium water?

First of all, a surplus of2 no less harmful than a disadvantage. It can cause gas embolism in fish when air bubbles appear in their blood. As a result, the fish may die.

Fortunately, such a phenomenon is rare. Nevertheless, you should not be zealous with aeration (for example, it is not necessary to install several compressors).

Please note that the rate of oxygen concentration is 5 mg / l and a little more. Measurements can be performed using special tests purchased at a pet store.

Changing water in small portions, controlling the composition of fish and the number of plants, regulating the flow of air from the compressor will help to achieve the perfect balance.



Aeration is the movement of water flow, as a result of which it is enriched with oxygen. During this process, air from the atmosphere passes through the thickness of the water layer, separating into small bubbles, which, when interacting with water, saturate it with oxygen (O2).

A large number of bubbles will provide better oxygen supply.

In the natural environment, aeration occurs simply – winds, underwater keys, plants create a current, but this is impossible in an aquarium. In a closed environment, the main supplier of2 there may be vegetation and special devices that create a stream of water with saturated oxygen.

Under normal aeration, the aquarium ensures the full activity of all living organisms.

Fish that can survive without oxygen in the aquarium

It’s no secret that oxygen is present in the aquarium in a dissolved form. Fish constantly consume O2 and emit carbon dioxide.

When an aquarium is artificially highlighted, the fauna highlights it during photosynthesis. To ensure a comfortable life for the fish without additional aeration, it is necessary to choose the right plants and settle the optimal number of inhabitants.

The most common problem is considered an imbalance in the number of green spaces and fauna. In the event that plants are not able to cope with providing all residents with oxygen, aquarists are forced to resort to using special devices for aeration.

The presence of oxygen in water is the main criterion for the life of almost all aquatic organisms. Aquarium fish are demanding on the saturation of water O2. This indicator can be called one of the main in determining the chemical composition.

Oxygen is essential for both fish and other creatures and plants. Each type of underwater inhabitants has its own requirements for aqua saturation. Some of them easily carry oxygen-poor water, others are sensitive to minor fluctuations.

Few people know that an excess of oxygen can also have a detrimental effect on fish. How to determine the optimal indicator?

If there is not enough oxygen, the growth of the fish slows down. This is primarily due to the wrong process of assimilation of food.

Creating an ideal ecosystem, consider that in addition to fish, oxygen is consumed by other organisms from the aquarium: ciliates, intestinal cavities, mollusks, crustaceans, and even plants in the dark period. It is not difficult to guess that the more inhabitants, the more oxygen they consume.

It happens that the wrong organization leads to the death of the fish. In the process of oxygen deficiency, fish begin to choke due to accumulated carbon dioxide.

Causes of oxygen deficiency:

  • High density of inhabitants;
  • High salinity and temperature of aqua;
  • The consequences of improper treatment;
  • Alkalinity jump.

As a result of the increase in the thermometer, the processes occurring in the body of the fish are intensified. This leads to an increase in oxygen consumption.

If the figures have crossed the mark of 28 degrees, then the fish begin to consume more O2 and emit a large amount of carbon dioxide, which leads to starvation and, if it is not urgent to react, then to the death of pets.

Lack of oxygen in a polluted aquarium is also dangerous. Various oxidation processes will occur in it, which will have a negative effect.

It is very important to monitor compliance with the number of tailings and water quality. Try to provide pets with high-quality filtration.

It is worth saying about bacteria, which are an integral part of the underwater world. The increase in the number of inhabitants leads to a large amount of excrement, which leads to an increase in the ammonia content of the water. All wastes that are subject to mineralization are carefully treated with bacteria.

Thus, the more organic elements, the more bacteria that also need oxygen. As a result, the circle closes.

If bacteria and fungi are O2 deficient, then they begin to more slowly cope with the goal. Return balance in the ecosystem, you can only increase the supply of oxygen.

But there is another side to the coin. Thus, high oxygen saturation leads to an increase in pH.

This situation is not welcome in the aquarium, because the difference in the water being replaced will be too global.

Pay special attention to the flora of your aquarium. Because plants are an amazing and very important part of creating the right microsphere. All plants produce oxygen during the day, but consume it at night!

It is necessary to take into account and do not turn off the aerator at night.

What aquarium fish live without oxygen and air

11.10.2013 added

In Asia, a lot of rice fields and it is there that live fish adapted to breathing atmospheric air. These are, in particular, labyrinths that have a labyrinth labyrinth organ (labyrinth).

It consists of winding canals, the walls of which are formed by bone plates covered with films with blood vessels. Contract labyrinth enters the perch-shaped detachment.
The labyrinth organ makes it possible to survive in water, where there is practically no oxygen. Moreover, if labyrinth fish interfere with breathing air, it will die even in oxygen-saturated water. Therefore, keeping such fish in an aquarium, it is necessary to ensure that floating plants do not completely cover the surface of the water.

And there is also the African labyrinth fish – Ktenopoma.

Video about labyrinth fish that breathe atmospheric air

a selection of photos of fish that do not need oxygen

Since there are no such fish that can live without oxygen, it is necessary to figure out, and do the “double-breathing” hydrobionts need any special conditions? Yes, and the main condition – mandatory aeration in the aquarium. Such inhabitants can live in an aquarium in which there is access to atmospheric and diluted O2 in water.

Gathering on a long trip, an aerator is also needed to save the lives of these pets. The gap between the aquarium cover and the surface of the water should be slightly open so that they can breathe in their portion of air.

How do medications and elevated temperature of water affect the oxygen supply?

When the fish are sick and sitting in quarantine, drugs can save them from the disease. However, instead of adding drugs, it is often necessary to raise the temperature of the water so that the fish become healthy. This applies to heat-loving tropical species, which become lethargic and weak due to the decrease in temperature in the reservoir.

As a rule, when adding drugs, they increase aeration, since substances block oxygen supply to water. Therefore, the presence of a good filter is an additional help that will help the exchange of oxygen around the water perimeter.

Increased temperature also limits the flow of oxygen into the water, so aeration should be enhanced. This is important for cold-loving fish and amphibians that need oxygen.

Powerful aeration and lowering the temperature of the water in the aquarium to the permissible rate will quickly eliminate the problem.

What to do if you have to transport the fish over a long distance?

Signs that determine that fish need more oxygen

What fish can live without oxygen and filter :: aquarium fish breathing atmospheric air :: Aquarium fish

Many fish intended for keeping and breeding in captivity, can not do without oxygen and filter. But not all! There are wonderful aquarium fish that freely do without an aerator.

Name them – betta, or cockerel.

The question “opened a pet store. Business is not going. What to do? “- 2 answers

1. The main advantage of these fighting fish is that they can live without oxygen and a filter. The fact is that cockerels breathe atmospheric air.

Moreover, they don’t even like to live in an aquarium equipped with a filter, since such a “dwelling” is oversaturated with oxygen, and the current created by the compressor only scares them. Of course, one should not argue that cockerels can live well in three-liter jars, but the fact that they feel great in a small aquarium without any filtration and aeration is an indisputable fact!

2. That’s just the breeding of these fish can cause some difficulties, and not everyone wants to become a professional breeder. Many people generally keep cockerels for enjoying their beauty. The cockerels are not whimsical in the rest of the service: they feel great in stale water, and also have no increased appetite.

However, this does not mean that the males need to change the water every six months and feed them once a week. Not!

3. Betta aquarium fish (or cockerels) are members of the labyrinth family. It is no coincidence that these fish have been dubbed “cockerels”. The fact is that their color and combative fighting character reminds of beautiful and cocky cocks.

For example, if you put two betta males in one aquarium, then a real cockfight with loose fins and tails can begin. If time does not separate the “fighters”, then one of them will die.

4. In general, cockerels are descended from Vietnam, Indonesia and Thailand. There they live in warm and small reservoirs with stagnant and silted water. That is why an aerator is not needed for saturating an aquarium with cockerels.

Males have an oval body, elongated in length and slightly compressed at the sides. The length of the calf of males reaches 5 cm, and in females it is 4 cm. Dark stripes are arranged along or across the body of the males.

Upper fin has a rounded shape. The bottom starts from the head and comes to the tail.

The pectoral fins of cockerels have the correct pointed shape.

5. It is believed that the beauty and uniqueness of color is not equal to these fish. The males are motley, and their colors shimmer from red to pink, from pink to yellow, from yellow to orange, from orange to green, taking all sorts of shades. Especially bright color can be observed in males, arranging a “cock” fight.

It is curious to watch the fish even when they inflate their gills in an excited state, forming a kind of bulging “collar” around their head.

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