Do Angelfish Need Oxygen & Filters?

Disclosure: When you purchase something through my affiliate links, I earn a small commission. As an Amazon Associate, I earn from qualifying purchases.

When I started with angelfish, I asked myself whether or not they require oxygen diffusers or filters. Some fish, like bettas, can do just fine without them. To make sure I don’t cause my angelfish any harm, I began researching.

Yes, angelfish need oxygen diffusers and filters since water features 95 percent less oxygen comparing to air. Also, in their natural habitat, environmental factors like wave movements consistently dissolve oxygen into the water. Since aquariums lack such turbulence, filters, and diffusers are a necessity.

However, in certain circumstances, bubbles can stress your angelfish. Also, some tanks require more severe means to keep the water oxygenated. Keep on reading to make sure your fish receives the best conditions possible.

Also Read: Facts About Angelfish

Do Angelfish Need Oxygen?

If you are struggling to find oxygen diffusers online, don’t worry too much about it. The name tends to change. Some people call them aerators. Others prefer terms like ‘Air Pump’ and ‘Bubbler.’

You could argue that some of those names refer to particular devices. But people tend to use them interchangeably, so in many cases, it doesn’t matter.

Once you tell an expert what you expect out of your device, they will tell you whether you want a bubbler, a diffuser, or an air pump. Some people lump water pumps into this category.

Regardless of your choice of terminology, the objective of a diffuser remains the same. You use it to introduce oxygen into the tank.[1] The device does this by agitating the water.

The turbulence generated on the surface, not to mention the upward motion of the bubbles, will allow oxygen to enter the tank while carbon dioxide escapes. Like all fish, angelfish require aeration. Diffusers ensure that oxygen is adequately disseminated throughout the entire tank.

Why Diffusers Matter to Angelfish?

Diffusers allow oxygen to dissolve in the tank water. But why does this matter? Well, most of you can probably guess the answer. Like humans, fish breathe oxygen. They consume it to keep their bodies alive. Without it, they will not survive. 

But as you might have also guessed, fish don’t breathe oxygen like humans. They live underwater. Their gills, which are reminiscent of feathers, are designed to extract oxygen from the water. Most people know that water is already filled with oxygen.

It enters via the surface. Even in a tank, you can trust that the water has oxygen. So why does a diffuser matter? The answer is simple. There is 95 percent less oxygen in the water than there is above water.[2] Angelfish are efficient creatures that can extract roughly 80% of the oxygen in the water that passes over them.

So they can make do with the quantities they encounter. Nonetheless, oxygen is a precious commodity, and angelfish cannot rely on its consistency. Out in the oceans and lakes, certain environmental factors can cause oxygen levels to drop drastically.

In a fish tank, it is even easier for oxygen levels to deteriorate. This is why diffusers are so essential. You need to keep them on hand to ensure that the oxygen levels in your tank are consistent. This is the only way to ensure that your angelfish are healthy and happy.

If you have ever seen your angelfish gasping for air near the surface, they were probably fighting to drink the film of oxygen-rich water near the surface because the oxygen levels below had dropped. 

In such situations, rather than running to the store to get a diffuser, you should take a moment to stir the water. This will give your angelfish some relief while you take steps to remedy their situation.

Do Angelfish Need a Filter?

Filters are not diffusers. They do not perform the same core function as diffusers. However, many professionals argue that anyone who has a filter does not need a diffuser. 

As its name suggests, a filter is designed to filter the water. It can do this chemically, biologically, and mechanically. Mechanical filters are the most obvious. They are physical systems that strain the water, catching and removing debris from the tank.

Filters are supposed to keep the water pure and clean. That also means eliminating the waste that fish excrete. This is where the biological filtration process enters the picture. Some bacteria break fish waste down, preventing it from corrupting the quality of the tank.

Chemical filtration involves the use of substances like zeolite to remove compounds that cause harm to fish, such as ammonia and nitrates — honestly, all three forms of filtration matter. 

Without a filter, the quality of your tank water will deteriorate to a point where your angelfish will begin to suffer. Not only will they grow sick and distressed, but their chances of dying are quite high.

As such, you shouldn’t let anyone deceive you into thinking that you can get by without a filter. This is the one tool that your angelfish desperately needs. In some cases, you have to cater to each category of filtration individually. But you can also find filters that perform all three forms of filtration.

Now that you know what a filter does, you are probably wondering why its presence makes a diffuser unnecessary. After all, a filter strains the water while a diffuser maintains the levels of oxygen in the water. These two functions couldn’t be more different. Where does the conflict emerge?

As was mentioned above, diffusers keep the tank aerated by simply agitating the water. This allows carbon dioxide to escape while oxygen enters. That sounds like an important function. 

However, in straining the water, your filter will also cause turbulence.

And by agitating the water, the filter will also allow oxygen to dissolve into the water. In other words, a filter can do the work of filtration and aeration.

Admittedly, the aeration aspect of the filter is merely a side effect of its operations. It isn’t the core function of the device. And you might encounter cases that specifically require the power of a diffuser.

But in most cases, filters are perfectly adequate. Anyone who has ever used a power box filter can tell you as much. These hang on the back of the tank. You also have canister filters that connect to the tank via tubing (they usually stay out of sight) and sump filters, which feature a separate fish tank filled with all the filtration tools your angelfish require. 

When Are Diffusers Necessary For Angelfish?

As was mentioned above, diffusers are not necessary if you have a decent filter. But there are plenty of reasons that could compel you to acquire one regardless, for instance:

Hot Climates

If you live in a tropical region, you might want to keep a diffuser around for emergency purposes. High temperatures can deplete the oxygen in a fish tank. This is because warm water doesn’t hold onto oxygen quite as effectively. If you see your fish gasping for air at the surface on a hot day, install a diffuser. It will bring relief.

Also Read: Can Angelfish Live In Cold Water?

Deep Tanks

Some tanks are better suited to diffusers than others. A shallow aquarium typically has sufficient oxygen because it has a larger surface area. Hence, the oxygen that pushes through the surface of the water can efficiently work its way to the bottom. 

For this very reason, a deeper tank will present a problem because it has a smaller surface area. The oxygen doesn’t get quite as far, not as quickly as you might want. A diffuser will resolve this issue by stirring the water to ensure that oxygen is satisfactorily distributed throughout the tank.

Numerous Fish

Like humans, the more fish you have in a tank, the more oxygen they will consume. If you have chosen to overstock your tank, be sure to add a diffuser. This will ensure that the aquarium has enough oxygen to cater to the needs of all its inhabitants. 

Diffusers produce bubbles. Specific devices, such as bubblers, tend to produce more bubbles than others. Some angelfish like these bubbles. If this applies to your fish, get them a diffuser. But you should know that some fish do not like bubbles. Keep this in mind before forcing a diffuser on them and exerting unnecessary stress. 

Pleasant Appearance

Some people add diffusers to their tanks because they love the look. A bubbler, for instance, is a porous rock (it can be made from other material) with an airline and an air pump.

Some people appreciate the addition of the air rock to the aesthetic of their tank. If you are one such person, no one will discourage you from adding a diffuser to your tank.

In fact, you are generally encouraged to install a diffuser whenever you think it necessary. If you notice that your tank doesn’t have enough oxygen, even if you cannot identify the cause, do not hesitate to add a diffuser. It is better to be safe than sorry.

How About Water Pumps For Angelfish?

Water pumps are used in aquariums that are too large for diffusers to work. A diffuser that cannot stir the water sufficiently because of its considerable volume doesn’t serve much of a purpose. 

This is what happens with diffusers in large aquariums. They are too small to effect significant change, which is why water pumps are used. They have the strength to oxygenate the water in large tanks properly.

Keep in mind that there are water pumps with filters that perform the functions of a filter and a diffuser. If you own a relatively large tank, don’t hesitate to get a water pump for your angelfish. 

Can Diffusers Be Dangerous For Angelfish?

It was mentioned above that you could add a diffuser to your tank for aesthetic purposes, even when you don’t actually need it. But can diffusers cause harm to your fish? It depends on the diffuser and the fish. Some angelfish hate the bubbles that air pumps generate.

They experience stress as a result. In such cases, you could do more harm than good by adding an air pump to your tank. Some pumps are also quite noisy. So you should keep that in mind before buying one that you do not need.

One way to know if your angelfish are stressed is by observing their bars. When they feel uncomfortable, their stripes begin to fade.

How to Ensure Your Angelfish Are Adequately Oxygenated?

Are there ways to ensure that your angelfish always have the right amount of oxygen in their tank? Well, there is no way to determine the exact amount of oxygen that each aquarium should have. But you can increase the chances of avoiding an oxygen deficit by keeping the following in mind:[3]

  • If you have decided to use a filter rather than a diffuser to maintain the oxygen levels in your tank, make sure you choose a filter that is adequate for the size of your fish tank. You can make do with one that is rated for your tank size, but experts encourage the use of a filter that is rated for a larger tank. This will deliver optimal results.
  • Even with the best filters and diffusers, things can happen to leech the oxygen out of your tank, the most prominent being overstocking. For this reason, you need to keep an oxygen test kit on hand. This will allow you to keep an eye on the oxygen levels in your tank.
  • If you don’t have a testing kit, watch the angelfish. If they are gasping for air at the surface, you probably have an oxygen problem. You can come to the same conclusion if your fish are moving slowly. In some cases, you will notice that the gills are moving rapidly. This tells you that the levels of oxygen have dropped. You should always act quickly in such situations.
  • Don’t forget to introduce plants into your tank. Plants take in carbon dioxide and push out oxygen. In other words, they will increase the oxygen levels while also reducing the carbon dioxide volume.
  • If overcrowding is the cause of your tank’s oxygen deficit, try reducing the number of fish. 
  • Make sure your filter is working. One common cause of oxygen deficits is a spike in the quantity of waste. Components like ammonia and nitrites will debilitate the water’s ability to hold oxygen. Excess algae can produce similar results. One solution is to use powerful filters and algae cleaners. You should also change the water. 
  • It was just mentioned above that plants take in carbon dioxide and release oxygen. This makes them useful because you can rely on them to keep the oxygen in the tank at optimal levels. However, when there is no light, the plants will consume oxygen and release carbon dioxide, which is not good. Also, too many plants can deplete the oxygen in your tank. To solve this problem, avoid overcrowding your tank with plants. 

Also Read: Do Angelfish Need to be in Groups?


Do angelfish need diffusers and filters? Yes, they do, but for different reasons. Diffusers and filters don’t perform the same functions. In fact, some people have argued that most tanks do not require diffusers in the first place. 

Whether or not you agree with them depends on your situation. Either way, the water in your tank must feature turbulent currents. You may achieve that by using a diffuser but also with a filter. The last will also clean the water from debris byproducts.