How To Increase Oxygen In a Fish Tank? Does Low-Oxygen Level Matter?

Just like human beings, fishes need oxygen for breathing. However, living in natural environments is not the same as in aquariums. One of the most fundamental differences is oxygen degree. Due to the lack of surface water, fish tanks have the lowest level of oxygen. And as you know, if fishes can’t get enough oxygen to breathe, they will suffer from several health issues. 

Therefore, you should pay attention to the oxygenation and aeration of your aquarium. In this article, we will discover “How To Increase Oxygen In A Fish Tank?”. In contrast, is excessive oxygen levels actually good or bad?

What Are The Signs Of Low Oxygen In Your Fish Tank?

The primary thing is to recognize the symptoms of low oxygen levels. The most apparent sign is your fishes’ behavior.   

If the oxygen levels drop too low, fishes tend to move around and eat less than usual. On a much severe level, they will start to display labored breathing, as well as rapid gill movements. These are the signs indicating that your fishes are in need of more oxygen. 

In addition, fish also gasps with a wide-open mouth at the surface when the oxygen in the tank is not enough. While some species of fish usually come to the surface, it is unusual for all of the fishes to gather there frequently.  If you have ever seen this situation before, then take a closer look at your aquarium’s oxygen level.

How to Increase Oxygen in An Aquarium? Urgent Methods

In case when you realize the oxygen insufficiency too late while your fishes need instant air, here are some urgent methods. But, remember that they are just short-term solutions. You still need to seek more durable and effective options.

Make an extensive water change

A fast way to provide more air for your fishes is to pour in new water. As the introduced water supplies enough dissolved oxygen, it can temporarily increase the tank’s oxygen level. The recommended amount is up to half of the tank.

Use Battery-powered Air Pumps

More water movements support better oxygen exchange. In case you encounter a power cut, using battery-powered air pumps is the best alternative option. 

Discharge water from a height

You can manually oxygenate your small aquarium by slowly pouring water from some height above. As the water is poured down, it will pick up the air on the way and drive oxygen into the fish tank. The amount of oxygen depends on how high you pour the water and the frequency of this process.

These simple steps are:

  • Step 1: Take a clean cup, jar, or other containers, fill it with water from your fish tank
  • Step 2: Hold the filled jar and pour the water back to the tank from a height above.

Here is a useful tip for better convenience. To avoid stirring up the substrate when pouring water, try putting a bowl or a small plate in the tank. Note that it should be weighty enough to stay put at the tank’s bottom. Then, flow the water over this area.

Make use of ice cubes

High water temperature is another common cause of your fish tank’s low-oxygen. If that’s the case, then you can use ice cubes to cool the water down temporarily. Put some cubes into the zip-closed bag, then throw it into the aquarium.

How to Raise Oxygen Level in Fish Tank? Long-term Solutions

The oxygen levels of your fish tank should be supplied continuously. It is unhealthy to let your fish suffer from the lack of oxygen several times, isn’t it? That’s why here we have the long-term methods for raising the oxygen level.

Increase Fish Tank Surface Area

Your fish tank size and shape matter a lot to the efficiency of gas exchange. As this process happens on the water surface, the oxygen is introduced into the tank. So to say, the amount of dissolved oxygen in your tank is largely affected by the surface area. In order to get the optimal gas exchange result, choosing the proper aquarium is essential.

Increase Surface Agitation

The surface area is also influenced by water movements on the surface. When the surface water is agitated, it constantly changes the layer of water coming into contact with the air. That means the more movements, the larger the surface area. And consequently, you will have better gas exchange outcomes. 

Here are some common ways to achieve higher surface agitation:

  • Use An Aquarium Spray Bar: 

A spray bar is commonly attached to the filter outlet. It basically sprays the filtered water evenly across the aquarium surface. Thus, it supports better aeration by providing more exposure to water.

  • Use Air Pumps: 

Air pumps are a pretty common choice due to its straightforward function. It takes the air then flows back into the tank through an airstone. In addition, there are a variety of air pumps’ shapes and sizes for your preference.

The video below shows fishkeepers how to use an air pump and air stone to introduce more oxygen into the tank, watch it!

  • Use a HOB filter:

HOB filter is a small and easy tool that every fishkeeper should have in hand.

This equipment is installed on the back of the aquarium. Its purpose is to release the filtered water back to the tank from a height. Thus, water aeration is promoted, facilitating better gas exchange.

Other available options to raise surface agitation are using aquarium wavemakers, powerheads, or a fountain (if your fishes live in a pond).

You can learn about the best HOB filters for small aquariums here.

Manage Your Fish Quantity

Depending on the size of your fish tank, it can only manage a certain quantity of fishes. The more fish in your tank means the more oxygen needed. If you have too many fishes, the amount of necessary oxygen will not be guaranteed.

Clean Your Tank Properly

Another common cause of your tank’s low-level oxygen is waste. High amounts of nitrites and ammonia in fish waste also cause dissolved oxygen depletion. In the worst circumstance, it may cause accumulated ammonia or nitrite poisoning.  

Like excess wastes, the overgrowth of algae obstructs the tank water’s oxygen-carrying capacity as well. So, to keep your aquarium healthy, you should perform tank cleaning regularly along with a large water change.   Keeping your fish tank cleaned out of algae and waste should help the water to carry a higher amount of oxygen. Besides, you should clean the filter too, since it can help to get rid of more water waste.

Watch Out Of Your Plants

Though it seems unrelated, aquarium plants influence the oxygen level as well. We know that plants absorb CO2 and produce oxygen. However, it is true only under proper lighting conditions. When you turn off your tank’s light, plants will do the opposite thing: they use up oxygen and give off CO2. Consequently, the oxygen supply of your fishes is greatly reduced.

So, the best thing to do with these live aquarium plants is to extend the light hours per day. You can combine the use of good LED for aquarium with a natural light source to increase the time to provide light for aquatic plants. You should consider removing some species as well, especially caladium, Dracaena plants, crimson ivy, and plants with variegated foliage.

Manage Temperature Rises

At colder temperatures, water can hold a higher amount of oxygen than at warm temperatures. Therefore, more fresh oxygen will be introduced into the tank by adding cool water. 

On the other hand, any temperature rise eventually leads to less oxygen supply in the tank. To avoid this, you can turn off the heaters and lights. Especially, do not let your aquarium come into contact with the sunlight. Heaters should be turned off, as well as lights. 

If your tank temperature varies just within a few degrees, using a fan will be an easy choice. While facilitating better air blowing, it also helps to cool the water to an appropriate level. For a temporary result, you can make use of ice cubes, as we have mentioned above.

Notice Medications and Chemicals

You should be aware that chemicals and medications have a two-sided effect. While it may be used for treating a specific water problem, it also contains an adverse impact on the water’s oxygen-carrying capacity. Therefore, whenever you put anything into your tank, it is necessary to read the label and instructions carefully. You should make sure that the added substances do not harm the dissolved oxygen levels of water.

Is Excessive Amount Of Oxygen Good?

So far, we have found ways on how to increase oxygen in a small aquarium. Yet, on the contrary, does too much oxygen do harm to your aquarium as well?

The answer is YES. If you oxygenate your tank at an excessive level, it will bring much harm, though. A common lethal disease is the gas bubble. It is caused when the gases are formed in the fish bloodstream, creating bubbles in their anatomy. As the condition worsens, the bubbles on the fish’s fins, eyes, and gills become visible. While inside the body, these bubbles concentrate at the fish’s heart, eventually causing death.

The Bottom Line

Though fishkeeping is a stress-free hobby, you still need to take proper care of your fishes and aquarium. One of the most common questions is “How To Increase Oxygen In a Fish Tank?”. Your fish surely cannot live for long when staying in a low-oxygen environment. If you encounter this problem, look into your tank situation and try following our solutions above. We hope that we can help you enjoy your aquarium hobby better. Thanks for reading!

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