When choosing fish for an aquarium, many fishkeepers are concerned about which fish can live without oxygen. Like all living things on the planet, fish need oxygen, which can be atmospheric or diluted in the water. As for the air in the aquarium environment, some phenotypes can live without oxygen.
Here is the list of fish that can live without oxygen:
- Spined loach
- Kuhli loach
- Paradise fish
- Dwarf gourami (lalius)
- Siamese fighting fish
- Thick-lipped gourami (labiosa)
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What fish can live without oxygen?
On the Internet, more and more people are trying to get the answer to the question: which fish can live without oxygen? However, the solution does not quite suit them. It is impossible to find at least one living creature that can live in a bowl or an aquarium without oxygen. But some aquarium inhabitants can survive without a water aeration system or an air pump.
The difference between those fish on the list from others is that they tolerate low oxygen levels or breathe atmospheric air. Due to this ability, they are considered the most enduring and unpretentious fish species to care in an aquarium without an oxygen system. There is a small list of fish that don’t need oxygen, and, unfortunately, not all species were able to adapt to low oxygen aquarium life. Such fish are:
- Aquarium catfish or loaches. These fish species use intestinal breathing with atmospheric air to consume oxygen. It happens pretty simply. A catfish rises to the surface, swallows air, and sinks to the bottom.
- Anabantoidei (labyrinth). They got their name because of the unique breathing apparatus, which is also called the branchial labyrinth. The air absorption process is similar to the previous one. The most popular aquarium representatives are siamese fighting fish, gourami, dwarf gourami, and macropods.
You should bear in mind that the absence of aeration and filtration necessitates increasing the frequency of such aquarium care tasks as cleaning with a siphon, changing water, and conducting tests.
With the help of tests, you can find out the content of useful and harmful substances in the aquarium water, especially in small fish bowls, such as nitrogen, which is detrimental to fish.
In their natural environment, the inhabitants of stagnant water ponds and reservoirs use skin respiration. The amount of oxygen consumed through the skin in inadequate water quality reservoirs reaches up to 80% when the standard figure is around 20%.
Some fish can live and feel comfortable without oxygen and aeration but with good filtration.
If you have to maintain an aquarium or a bowl without filtration and aeration, then it is necessary to select the species and breeds of fish carefully and strictly combine the number of fish with the tank’s volume. For this, please read about our list of fish that can live without oxygen.
The spined loach (Cobitis taenia) lives throughout Europe. It got its name from its characteristic spine curve.
Before the weather changes, the fish begin to worry, swim actively, and capture air from the surface more often. In a calm state, the fish also breathes atmospheric air but rises to the surface less often.
The air concentrates in the middle section of the intestine and passes to the back section, enriching the blood with oxygen through the tiny capillaries in the intestine. And because of that, it is on the list of fish that can live without oxygen.
But intestinal respiration accounts for about 20% of total breathing, and about 60% of oxygen is absorbed through the skin, while another 20% falls on gill respiration.
These indicators are relative and depend on living conditions. Accordingly, if the water in the aquarium is low in oxygen, the loaches will extract it from the atmosphere.
Sometimes loaches, having intestinal respiration, burrow in the substrate, so they do not rise to the water’s surface because the swallowed air bubble in the intestines lifts them, so drifting loaches float to the surface.
Spined loach care tips:
- A reservoir with a volume of 10 liters is suitable for breeding;
- No sharp decorations;
- Use coarse and fine soil;
- The temperature can range from 3 to 30 degrees Celsius;
- Food can be standard. If you give it something, the loach will show you what it likes;
- Harmless fish but prefer the same neighbors.
Kuhli loach fish looks like a mini-snake or a sizeable yellow worm with a black stripe. It is from the carp family. They prefer a temperature of around 25 ° C.
It uses atmospheric air as oxygen enrichment, which passes through the intestines. In addition, kuhli loach can absorb oxygen through the skin. To carry out the skin respiration of this fish, there must be oxygen in the water.
An aerator to increase oxygen level is not necessary. An incorporated air flute that works through an internal filter pump is perfectly suitable.
But just a filter is also suitable. The filtered water stream should be directed to the surface. Thanks to this, the water will be enriched with oxygen.
The Kuhli loach deserves a caregiving effort. Striped snake-like pets are distinguished by a peaceful disposition and a passion for solitude.
But they know how to stand up for themselves. Kuhli loaches have a sharp thorn under the eye. It is convenient to pave the way in sand, soft ground, and an irreplaceable defensive weapon. They can pierce predators’ intestines, sometimes ripping open their stomachs.
Conditions of keeping:
- They feel comfortable in small ponds;
- It is necessary to provide shelters in the form of snags, stones, castles;
- They do not need a special diet – microorganisms from the soil are suitable and waste from other inhabitants. Indulge in live, frozen treats;
- Can jump out of aquarium or bowl – a cover is required;
- They can get along with almost everyone.
Paradise fish are endurant species.
They are not demanding to the temperature and feel equally comfortable both at + 16 ° С and + 25 ° С temperature.
Very fertile and live very long. Resistant to cloudy water, cold. Paradise fish are pugnacious and do not tolerate small neighbors. The worst temper is among the dark representatives. The king of aquariums and one of the first types of the European aquarium hobby.
Filtration is mandatory. Experience shows that this is not the case.
Easy to breed in aquariums.
More about the habitat:
- It does not grow even in a 300-liter fish tank;
- Omnivorous – plant, protein food is suitable;
- Usually, people use coarse sand, expanded clay, small pebbles as soil. Narrow decorative shelters will not work – paradise fish cannot move backward. They will get stuck and die.
- It is advisable to add plants covering the surface of the water (Duckweeds);
- A cover is required that does not block access to atmospheric air;
- Average illumination level;
- They are not recommended for a shared aquarium with small defenseless fish.
Gourami fish are from the order of Perciformes, with a labyrinth organ. It is thanks to the structure of this apparatus that gourami extracts air and provide themselves with oxygen.
A prerequisite is an aquarium with unhindered access to atmospheric air. In Gourami fish’s natural environment, they were found in sewers, small, “stagnant” bodies of water, where water was with low oxygen levels.
Gourami and other labyrinth fish need access to atmospheric air. During transportation, oxygen pumped into the bag can destroy the fish since it burns the respiratory organs of such a (labyrinth) structure.
Kissing, pearl, marble, gold gourami fish are the most popular species. They can live up to 6 – 8 hours without water. Friendly, curious, playful.
Recommendations for gourami:
- The length of the aquarium is at least half a meter;
- Volume from 50 liters;
- A lot of floating plants;
- Shelters are required and space for free movement;
- Dark soil emphasizes the beauty, colorful, bright color of gourami fish and offspring;
- They are not picky about food. The menu should be varied. Delight them with herbal, dry, lively dishes. Overfeeding is not recommended.
- Will make friends with dwarf gourami, other peaceful labyrinths, loaches.
Dwarf gourami (lalius)
Yes, dwarf gourami too goest to the List of fish that can live without oxygen. They are shy. Stay in the flocks of three individuals to feel more confident. They live for about 2-3 years.
Dwarf gourami is a small, bright fish with a labyrinth respiratory apparatus belonging to the family of gourami.
They do not require special care with no whimsical food and maintenance requirements. Dwarf gourami will feel more comfortable with a filtration system installed.
The aquarium cover will prevent the inhabitants from jumping out of the aquarium. And if good lighting is included in the lid, the plants will grow more actively, creating a different diet for the fish and a favorable microenvironment.
The following conditions are comfortable for gourami fish:
- Aquarium volume from 15 – 20 liters;
- For breeding, thickets of plants are needed in the corners of the aquarium;
- They do not belong to gourmets, but monotony in feeding is destructive. Balance protein with plant foods;
- They prefer calm, non-aggressive neighbors, such as guppies.
Siamese fighting fish
Siamese fighting fish(betta fish) is the most famous representative from the list of fish that can live without oxygen. Under suitable conditions, these fish live up to 3-4 years. They are not demanding to care, but an aquarium or a bowl should be clean. Three liters is enough for one fish. This makes betta fish one of the best fish that can live in a bowl with no oxygen. Betta fish absorbs atmospheric air, floating from time to time to the surface, capturing an air bubble from which it produces oxygen.
Siamese fighting fish are often chosen as a single pet in an aquarium or a bowl. But driftwood, algae, grottoes, lighting will make its life more joyful.
The water changes should be carried same as with other fish species:
- At least once a week, in containers from 10 to 20 liters.,
- If the aquarium is up to 5 liters, then add fresh water two times a week.
The Siamese fighting fish lives little but vividly.
Aggressive bullies are ready to destroy weak, small, clumsy relatives or other fish.
- For one fish, 5-10 liters of water;
- Live, artificial plants, and decorative items are necessary for breeding and shelter from an aggressive male;
- Use on them various food types, but they are not picky. Unique mixes for betta fish are on sale;
- They do not get along with labyrinths.
Thick-lipped gourami (labiosa)
This representative of the labyrinth fish is often mistakenly referred to as gourami, calling them honey subspecies. Nevertheless, this fish is called labiosa of Trichogaster (until 2017, the genus Colisa).
The similarity with gourami is extreme, both externally and in conditions of care. But they usually grow larger, up to 9 cm.
The aquarium, which contains labiosa, must be equipped with a “cover,” that is, close the top to prevent them from jumping out of the “house.”
The cover is also needed to maintain the microclimate above the water so that the fish does not catch a cold while absorbing oxygen.
Thick-lipped gourami is a large and quiet one. The male’s purple color indicates his arousal. Suitable for multi-species breeding.
About the conditions of detention:
- 10 liters of water per representative;
- They love algae (Echinodorus, Waterweeds, Cryptocoryne);
- Special attention to water temperature (+ 25 … + 28 degrees);
- A small variety of food is suitable;
- Like any peace-loving fish can not tolerate restless aggressors.
However, do not expect that these animals can live entirely without air. They need it, so in no case access to the air is blocked.
Catfish are popular fish for aquarium lovers have a special place in the list of fish that can live without oxygen. There is an opinion that catfish do not need air, but this is not entirely true.
Some species absorb oxygen from the atmosphere, and some catfish do not need high oxygen enrichment. For example, corydoras paleatus have intestinal respiration, extracting oxygen from the atmospheric air.
Ancistrus, Pterygoplichthys, and other L-catfish require good oxygen enrichment, while thoracata and dwarf suckers can get by with a small amount of oxygen.
Catfish live in the lower layers of water bodies. Constantly cruising along the bottom and by digging the soil, they raise the dregs from the bottom. A small filter pump in an aquarium with catfish will provide filtration and enrichment of water with oxygen ensuring good health and contrast color.
Guppies are one of the most common aquarium fish. They are distinguished by the simplicity of care, unpretentiousness, lively character, and abundant colors. The homeland of these fish is the flowing ponds and rivers of Central and South America. Nowadays, guppies are common on almost all continents. Guppy fish in nature is very different from modern breeding forms: wild guppies are less colorful and bright and live longer than in an aquarium, about 3-4 years.
This fish is the best for newbies in fishkeeping. It is elementary to keep guppy in a bowl without oxygen. The size of the fish is small: males grow about 3-4 cm, females about 5-6 cm. Males are famous for their luxurious veiled tails. However, there are varieties of guppies with modest tails – forks. The guppy color can be either one color, yellow, or multi-colored, for example, a blue cobra.
They don’t need much oxygen and can live in a small fishbowl.
How long can fish survive without an oxygen pump?
Fishkeepers who are new to the hobby sometimes overlook the extra equipment necessary to maintain fish in a proper environment. Consequently, it is critical to have water rich in oxygen, which benefits the fish’s essential activities and stabilizes the detrimental indicators.
If you have fish not represented in our list of fish that don’t need oxygen, you have to be careful! There are fish kinds that will die without an air system in a matter of days, like discus fish. Check out if your fish kinds need sufficient oxygen in the water. If it does, you must immediately fix the problem.
It is not always possible to have water with an air pump. This is particularly true when the power source shuts off unexpectedly, fish are transferred over long distances, or the aquarium undergoes a thorough cleaning. In this instance, the issue becomes whether fish can survive without an oxygen pump?. Because the water already contains sufficient oxygen molecules, fish may live for long hours without mechanical ventilation and get additional oxygen by swimming to the surface and inhaling atmospheric air.
If the problem persists, a small volume of water should be replaced with new tap water to compensate for the fish’s lack of oxygen. Additionally, you may add 3% pharmaceutical oxygen peroxide to the tank (4 ml per 10 liters of water). This will enhance the fish’s condition, allowing them to swim at their typical depth for an extended length of time.
Signs of a lack of oxygen in an aquarium or a bowl.
Fish cannot live entirely without oxygen. However, you can make your life easier by buying fish that can breathe atmospheric air by noting our list of fish that live without oxygen. But even with a limited choice, you can collect the best representatives and create a unique reservoir where fish and catfish can live without discomfort.
Some of the signs of low oxygen in an aquarium:
- Fish rise to the upper layers;
- After a couple of hours, the fish start protruding their gills;
- Decreased appetite;
- The immune system suffers, visual problems with fish;
- Growth slows down, or fish start dying one by one.
Death may not occur, but the fish experiences constant discomfort and all life processes will pass slower, which affects the animal’s growth, color, and behavior.
The labyrinth is a specialized respiratory organ that allows some fish to absorb oxygen directly from the air. Labyrinth fish takes the air, “swallowing” it from the surface of the water. Therefore, such fish does not need aquarium aeration! However, if access to the water’s surface is closed, such a fish will soon die.
What are signs by which you can determine that the fish need additional oxygen?
If the fish often begins to take air from the surface of the water, even those that spend most of their lives in the lower layers of the aquarium, then this is an alarming signal. They need oxygen dissolved in water.
What measures should be taken in this case? First, measure the water for ammonia, nitrite, and nitrate. If harmful impurities are increased, replace 40-50% of water with clean, fresh, and acceptable parameters. Do not pour out all the old water at once. It is detrimental to the life of any fish. If the indicators of ammonia and nitrates, nitrites are normal, then increase aeration and add an air pump to the water.
Air pumps – what are they for and do you need them?
Air pumps are often built-in water filtration systems or separately. There are different types of such air pump stones in different shapes and sizes. They help the fish that breathe with the labyrinth organ and saturate the water with additional oxygen. Small air stones float on the surface of the water thanks to their lightweight and floating composition. Heavy air stones can be placed against the back of the aquarium for additional decoration. If you don’t like the noise, you can use air pumps with fish that we listed above only for a couple of hours a day.
Most labyrinth fish do not pose any particular problems in their care and maintenance. The volume of their aquarium or bowl does not play a significant role. Like all fish that do not need oxygen, they need some conditions for their care:
- The aquarium water temperature should be 24-27 ° C.
- The substrate used should preferably be of dark color – this enhances the coloration of the labyrinth fish, emphasizing their beauty.
- For females of this family, dense vegetation is essential so that there is a place to hide from aggressive males.
- Labyrinth fish are not particularly picky about food and willingly eat both live, dry or frozen food.
Keeping them together with representatives of the same species is often problematic. Many adults (most often males) show aggression towards fish that represent their species. It can often happen when the volume of the aquarium or a bowl is small.
For the aquarium to be peaceful and quiet, the water must be “old” or standing. Changing water provokes the reproductive instinct and causes aggression.
Fish that do not need oxygen generally require access to the air surface. In order to prevent the fish from jumping out, it is good to cover the aquarium with a lid. There must be at least 5 cm between the lid and the water surface. This way, you can easily keep your new fish without oxygen!