Types of fish that can live without oxygen in the aquarium

Although maintaining an aquarium is a rewarding hobby, there are drawbacks. For many aquarium hobbyists, making sure their fish have enough oxygen to thrive is one of their top priorities. Not all fish, though, need continuous aeration to survive. Certain species are ideal for aquarists searching for low-maintenance choices because they have evolved to survive in low-oxygen environments.

You’re in the right place if you’re wondering which fish can live without an air pump. Numerous fish species possess distinct adaptations that enable them to flourish in environments with low oxygen levels. These fish give your aquarium a distinct charm in addition to being tough.

You can create a beautiful and balanced aquatic environment whether you’re setting up a new tank or looking to add to an existing one by knowing which fish can survive without oxygen. Let’s investigate a few of these intriguing species and discover what makes them unique.

Which fish can live without oxygen supply

Fish use their gills to breathe. The gill petals are found on gill arches, which serve as their representation. Water flows through the pharyngeal gill slits during breathing, washing the gill petals, and allowing the oxygen it contains to dissolve into the blood. Fish must live in oxygen-rich water for all internal processes to function normally. Fish that are in low-oxygen water suffocate and die quickly.

But in the natural world, there is not much oxygen in the water in many reservoirs. Fish species that inhabit small reservoirs, swamps, ditches, and puddles have evolved to survive in these environments. These fish have evolved organs that enable them to breathe in atmospheric oxygen.

Fish that are able to breathe atmospheric air and survive in low-oxygen environments include:

  1. Labyrinth fish. These fish take in air with their mouths and direct it into a special labyrinth organ that communicates with the gill cavity. The labyrinth organ is formed by several thin bony plates covered with a mucous membrane that is abundantly supplied with blood. Oxygen from the air enters the blood.
  2. Species with intestinal respiration. These include loaches and some catfish. These fish have intestinal protrusions in the form of sacs on the sides of the body. The fish take in atmospheric air with their mouths, which enters these sacs. Through the thin wall of the intestine, oxygen from the air enters the blood.
  3. Species that use the swim bladder for breathing. These include representatives of the polypterid family. The swim bladder of these fish consists of 2 sections and communicates with the intestine. Atmospheric air captured by the mouth enters the swim bladder, where gas exchange occurs.

Gourami

Labyrinth fish, or gourami. Most species have bodies no longer than 10 cm. The ventral fins are filiform and have been converted into tactile organs; the body is graceful and has been flattened from the sides. Depending on the species, the color can range from brown to silvery to golden.

Gurami are found in Southeast Asian rice fields and shallow waters in the wild. These fish don’t require oxygen in the aquarium because they are suited to live in murky, low-oxygen environments. To ensure that the air layer above the water is warm, the aquarium should be covered with a cover glass. The fish’s labyrinth organ is harmed by cold air.

Bettas

Labyrinth fish are also bettas. They live in Southeast Asian rice fields and still waterways. In the years that the species has been kept in captivity, breeders have produced over 70 different breeds with varying fin colors and shapes.

Betta is a good choice for people who wish to start a fish without a filter in a circular aquarium. Male bettas are kept strictly alone due to their pronounced territorial behavior and intraspecific aggression. Bettas can be kept in a small aquarium because they don’t need much room to swim in; the water is changed two to three times a week to keep it clean.

Lalius

Lalius are fish that resemble labyrinths and are found in slow-moving streams, lakes that are overgrown with vegetation, and rice fields. The lalius has a body length of 6-7.5 cm. Red and blue stripes that are vertical in shape make up the pattern on the sides.

Lalius are housed in groups dominated by females. In an aquarium, Lalius can survive without air, but filtration is preferred. Since lalius are quite shy, it is advised to add plants to the aquarium to replicate their natural environment. The species dislikes a temperature drop below 24 °C and is sensitive to the amount of nitrogen compounds in the water.

Lyabiosa

Fish that resemble labyrinths, labioza are 7–10 cm long. The body is patterned with vertical stripes that are greenish-blue and brownish-red. Labioza naturally occur in Southeast Asian lakes and rivers that flow slowly and are covered in a lot of vegetation.

Among the labyrinth fish, labiosa are thought to be the most tranquil. They can be kept in big groups or in pairs because they do not exhibit intraspecific aggression. This species can survive in aquariums without heating because it can withstand temperatures between 22 and 28 °C. Plants, including floating species, are incorporated into the reservoir to create soft filtration in the absence of a strong current.

Macropods

Labyrinth fish, measuring 8–10 cm, are called macropods. They live in Southeast Asian stagnant water bodies in the wild. The fish have large, elongated fins with vertical stripes of red and blue on the sides.

Among the most hostile labyrinth fish are macropods. One male and several females are housed in groups. Because they are resilient and unassuming, macropods can be kept in aquariums without the need for a heater or filter. These fish don’t require oxygen to survive, and they can withstand temperatures between 15 and 26 °C without getting sick. If not filtered, the water needs to be changed on a regular basis.

Stickler

Stickler is a fish that inhabits the waters of Europe and belongs to the family Loach. Its body is elongated, measuring 7 to 15 cm. The body is light brown with numerous rows of rounded, dark brown, small, and large spots running the length of the body.

Sticklers are maintained at pH 6–8, dH 4–20, and temperatures between 3 and 30 °C. These fish are peaceful and friendly to all of their neighbors. Sticklers like to burrow into the ground and live on the bottom. These fish don’t need a compressor to be kept in aquariums because of intestinal respiration. The tank needs to have a lid on it because the loaches get anxious when the air pressure changes and may jump out of the water.

Acanthophthalmus

Representatives of the loach family are Acanthophthalmus. Their body is up to 12 cm long and resembles an elongated snake. Yellow-orange in hue, with broad, vertical brown stripes. Beneath the eyes are spines. Acanthopephalmus naturally occur in Southeast Asian rivers and streams that flow slowly.

The ideal temperature range for acanthophthalmus is 24-28 °C, pH 6-7.5, and dH 5-10 °. These aquarium fish can survive without oxygen because of intestinal respiration, but a filter is necessary because they require clean water. Acanthophthalmus prefer to burrow into the ground and conceal themselves beneath branches and other obstructions.

How long can fish live without oxygen

It is essential to add more oxygen to the water for fish that can only breathe through their skin or gills. Their longevity in an aeration-free aquarium is dependent on the conditions within. The fish will not live as long in an overcrowded small volume as they would in a large tank with only a few fish kept in it. Fish will not live as long in high temperatures as they would in low ones because of the solubility of oxygen in water decreasing and fish metabolism accelerating with rising temperatures. Additionally, the higher concentration of nitrogen compounds in the water shortens the life span of fish without aeration.

It is essential to reduce the water’s temperature and cease feeding fish in order to prevent fish deaths when the compressor is turned off. Fish should be divided into separate tanks if the aquarium is too full, with each fish receiving 5–6 liters of water. To lower the amount of nitrogen compounds, 20–30% of the volume is replaced with fresh water two or three times after the feeding is stopped. The fish then spend the next two to four weeks in an oxygen-free aquarium. The fish will not survive for longer than five to ten days if action is not taken.

Certain fish species are perfect for setups with little equipment because they can survive in aquariums without extra oxygen. These fish have special adaptations that enable them to breathe air straight from the surface, just like bettas and some types of catfish. These kinds will be discussed in this piece, along with choices for aquarists who would rather have a less complicated, low-maintenance tank.

Fish Type Description
Betta Fish Bettas are known for their ability to breathe air from the surface, making them well-suited for low-oxygen environments.
Guppies Guppies are hardy fish that can tolerate lower oxygen levels, but they still benefit from a well-maintained tank.
Goldfish Goldfish can survive in low-oxygen water, but they thrive better with adequate filtration and aeration.
Zebrafish Zebrafish can tolerate low oxygen but prefer well-oxygenated water for optimal health.
Corydoras Corydoras have the ability to gulp air from the surface, allowing them to survive in low-oxygen environments.

For novices and aquarium owners with smaller spaces, fish that can survive without additional oxygen are excellent choices. Because of their adaptability to a range of environments and resilience, these species are easier to care for.

Even though they can endure low oxygen levels, it’s still critical to keep your aquarium clean and well-balanced. Maintaining appropriate filtration and routine water changes will help keep your fish happy and healthy.

Without having to worry about complicated equipment, you can have a beautiful, healthy aquarium by selecting the right fish and taking care of their surroundings.

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Elena Grishina

Ecologist and aquarist with a special interest in creating balanced ecosystems in aquariums. Main focus — ecosystems that require minimal human intervention. I support a natural approach to aquarium care, where each element plays its role, helping to maintain harmony in a closed ecosystem. I promote sustainable aquarium keeping and respect for nature.

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