How To Increase Oxygen In an Aquarium For Fish To Breathe

About a year ago I realized how important sufficient oxygen was to my fish. The temperature rose and they were gasping for air. When trying to find the cause I learned how to effectively and quickly raise the oxygen levels in my fish tank.

Use the bubbles of an air pump or the output of a filter or pump to break the water surface. This surface agitation is the best way to increase oxygen in the long term. Do a water change to quickly increase oxygen levels. Live plants and a larger surface also increase oxygen levels.

It’s really important to know some of the techniques that I will talk about in this article. In some situations like a power outage, heat wave or broken aquarium heater the oxygen levels can become a risk to the health of your fish.

How To Quickly Increase Oxygen Levels

If you’re in a critical situation you’re not looking for a lot of unrelated information. This is how you increase oxygen levels quickly to solve a problem temporarily:

Perform a large water change to increase the oxygen level. If you’re in a situation where you must increase oxygen ASAP, remove 40 – 50% of the aquarium water and replace it. Water from the tap contains a lot of oxygen and will provide your fish with the temporary air they need.

Other ways you can solve a difficult situation is by adding an air pump with air stone. The bubbles created by an air pump will quickly raise the level of dissolved oxygen, but not in the way you think. It’s not the bubbles created by the pump that dissolve in the water, instead the desired effect is the resulting surface agitation.

All the air bubbles break the surface tension and promote gas exchange. All the oxygen in the tank enters the water at the water surface. It’s at the surface where the carbon dioxide leaves the water and oxygen enters it.

Raise Oxygen Levels in the Long Term

Now that you have the information to solve any demanding oxygen deficiency it’s time to permanently improve your tank. To increase oxygen levels, increase the amount of surface agitation. Surface agitation is a fancy way to describe disturbing the water surface. If you constantly keep the water surface moving there’s a lot gas exchange happening.

Gas exchange in our aquarium hobby is all about carbon dioxide and oxygen. Most of the times both gases enter our aquarium water as the fish we keep consume oxygen and the plants we grow consume CO2. When you’re adding pressurized CO2 the carbon dioxide will actually leave the tank, but that’s a different story.

You do not have to break the surface to agitate it. If you’ve got any filter outlet that’s spraying water in the tank it can go both ways. I’ll try to explain what I mean.

If your filter outlet is hanging above the water surface it’ll definitely create surface agitation as the water falls into the tank. However your filter output can also be positioned under water. If you aim it (from under the water surface) upwards towards the water surface, it’ll continuously move it. This movement does not have to break the surface and cause all kind of splashes, but it definitely does increase gas exchange.

Use Plants to Increase Oxygen Levels

Plants are a great way to increase oxygen levels in an aquarium. As you’ve once covered during basic biology lessons, plants consume CO2 and produce O2. This is true for giant trees but also for small aquarium plants.

It’s so amazing that plants actually help with the overall health and state of your aquarium! This is the reason I always recommend people to at least get some easy plants for their tanks like Java Ferns or Anubias plants. If you really want that oxygen benefit you need plants that grow as fast as possible. I’ve compiled a list of over 10 plants that are really fast growers which you can find here. I highly recommend you reading it as I’m sure everyone will learn a lot.

Why Should You Increase the Oxygen Level?

There are several causes that may lead to an oxygen deficiency in your aquarium. If the problem is severe you’ll find your fish at the surface of the tank gasping for air. This really is a scenario you never want to see for yourself. I’ll quickly list some of the most encountered causes.

  • Summer temperatures are a common cause of an oxygen shortage. I do not understand the science behind it, but warm water can hold less oxygen than colder water. During summer the room temperature can exceed the tropical temperatures of the aquarium water and pose a risk to your fish. When you find yourself in this situation, do a water change, increase surface agitation and try to cool down the tank to regular temperatures.
  • Heater malfunction does occur in the hobby as no piece of equipment lasts forever. Whenever a heater dies down your tank gradually cools down towards room temperature, but when they try to boil your tank you’re facing a different problem. In this case, the effect is the same as with summer temperatures.
  • Overstocked tanks contain way too much fish that all require oxygen. If your tank is overstocked you risk an oxygen shortage that’s harder to battle. You can perform a water change to fix the solution for a while, but in the long term you need to consider some serious changes.

You Can Prepare for Problems

Dealing with problems is always a struggle, but an oxygen deficiency for whatever reason is something that you can in fact prepare for. Especially if you’re in a region that’s susceptible to natural disasters, it can be convenient to spend some money on preparation.

One of the best ways to keep the flow and surface agitation going in every scenario is a battery powered air pump. They are available on Amazon and are super reliable in situations of crisis. Please note that the link to Amazon is in fact an affiliate link and I make a small commission of every purchase. If you decide to order through my site, I’m sure grateful for the support.

When trying to battle the heat of the sun you have to take some different precautions. The placement of your tank will prove to be important when room temperature is rising. Direct sunlight should be avoided at all costs and if you can place your tank in a room that generally stays cooler in summer your fish will be grateful.

Using frozen bottles of water is no effective way of cooling a tank (I’ve tried). The only way to quickly cool down the water is by doing a large water change, as tap water generally is cooler than room temperature. You can also place some fans aimed at the water surface that blow away the warm air. This is one of the most effective ways. It can be a real pain dealing with these kind of issues.

Bart Sprenkels

I have been keeping multiple aquariums since I was 18 years old. Just like many of you, I started with two goldfish but quickly learned they were not suitable for aquariums. Later, I switched to a tropical community tank and I also have two pet musk-turtles in a bigger aquarium. You can read more about me here.

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