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How Long Can A Fish Live Without An Air Pump? Few Hours?

How Long Can A Fish Live Without An Air Pump? Few Hours?

In most aquariums, air pumps aren’t exactly indispensable. They do impart some valuable advantages and are of great consequences, but your fish can make do without an air pump too. 

Take my advice with a pinch of salt – there are ifs and buts surrounding this topic. 

In this blog, I’ll shine a light on pretty much everything you need to know about fish and air pumps. Let’s start with:

How Long Can A Fish Live Without An Air Pump?

The answer to this couldn’t be any vaguer – fish can live without an air pump for just a couple of hours to forever. If the tank is oxygenated at all times through other mechanisms, your fish can go through their entire lives without requiring an air pump. 

However, a lack of an air pump can sometimes lead to a fish’s demise. If the tank’s oxygen level is very low and there’s no air pump to oxygenate the water, the fish will suffocate. And a fish that can’t breathe cannot go on for a long time. 

Before we discuss any more about the air pumps, it’s first important to understand how much oxygen fish need and how they inhale it, and the causes behind low oxygen levels in the tank. 

Where Do Fish Get Oxygen From?

Interestingly, the oxygen your fish breathe in the tank is not directly sourced from the water. Turns out that the supply of oxygen in a tank comes from the surrounding air. 

The oxygen naturally present in water is inseparable. Thus, fish cannot separate the oxygen atoms from hydrogen to use it.

So, the fish’s life depends on the gaseous exchange that takes place at the water surface – at the top, carbon dioxide from the water and oxygen from the surrounding air is exchanged. 

Oxygen is also dissolved into tank water through photosynthesis and increased aeration (water movement).

How Much Oxygen Do Fish Need?

The ideal amount of oxygen a fish requires varies depending on the fish’s species and your region’s elevation. For example, if your home is at a higher altitude, the water will hold less oxygen and vice-versa. 

Thankfully, we don’t have to measure how much oxygen fish need or meet any difficult parameters. If the fish is active and eating well, you can be assured that the tank’s oxygen level is enough. 

But if you were hoping for a numerical answer, here it is: oxygen saturation should be between 80-100%, and the dissolved oxygen (DO) level of 6-8 mg/l should be maintained. 

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What Causes Low Oxygen Levels In Water?

The most common reason behind low oxygen levels in tanks is cramming too many fish together. Increased water temperature and decreased water movement are also to be blamed. Excessive chemicals, too many live plants, and a dirty tank are also directly linked with low oxygen levels. 


To be honest, it’s quite unfair to subject fish meant to swim in endless waters of seas and rivers to the same few cubic inches of water for all their lives. So the least we can do is provide ample space for each of them in our tanks. 

Overcrowding is the number one reason behind oxygen depletion in tanks. Each fish has unique oxygen requirements and will use up available oxygen accordingly. 

If you keep fish beyond the recommended stocking density, there will not be enough oxygen for everyone, and they might suffocate. 

Higher Water Temperature 

Hot water cannot hold as much oxygen as cool water. So, if your tank water’s temperature is warmer, there’s likely not enough oxygen in it for the fish.

Turning off the heater temporarily and partially changing the water is an effective way to gradually lower the temperature and introduce fresh oxygen into the tank.

For most fish, the water temperature should fall in the 65-70 degrees Fahrenheit range. You can put a few ice cubes in a zip-lock bag and place it in the tank to lower the temperature as well. 

Just make sure the change is not drastic, and the temperature isn’t below the required temperature range for your fish. 

Still Water

Still water contains a meagre amount of oxygen. Thus, the tank’s water must be moved or agitated regularly to maintain an adequate oxygen level. 

Filters help increase the oxygen concentration since it moves water – so make sure to check that the filter is running at full capacity. If the filter is clogged, it must be cleaned or replaced. 

Dirty Tank 

Fish waste and algae overgrowth can sap oxygen from a fish tank as bacteria do their job to break down excessive organic matter. Therefore, maintaining water quality is of utmost importance. 

A proper tank cleaning and water change to remove debris and algae from the gravel and tank walls will enhance oxygen levels. 

Live Plants 

We’ve been taught that plants absorb carbon dioxide and release oxygen when exposed to light. But that’s not the entire truth. When the tank is dark at night, the process reverses. The plants will consume oxygen and release carbon dioxide. 

Pruning the plant overgrowth and increasing the lighting duration can help improve the oxygen levels. 


Certain chemicals used to treat different dish diseases can modify the water’s pH level and also tweak the oxygen level. 

If you need to use chemicals in the tank, err on the side of caution and increase water circulation for the entire length of treatment so that the required oxygen level is maintained. 

So, you see – the tank’s oxygen level can deplete for one too many reasons – some that are within our control and some not. So, although it may sound like overkill, I’d recommend getting an air pump. 

If it doesn’t cost much but improves the fish’s quality of life by many folds, why not buy one?

The Air Pump We Recommend For Your Fish Tank 

Tetra Whisper Air Pump (for tanks sized 10 gallons to 100 gallons) 

Tetra Whisper Air Pump (for tanks sized up to 300 gallons)

I use Tetra’s air pumps in all my fish tanks. In my experience, the air pumps really live up to their name – super quiet operation. Plus, the build quality is decent, and it’s a name we can all trust. 

4 Reasons To Install Air Pump In Your Fish Tank 

It’s clear that an air pump isn’t an absolute necessity. However, they impart several benefits and are a bang for the buck. There are many unlikely benefits of owning an air pump, from encouraging gas exchange to amping up the tank’s aesthetics. 

Let’s discuss them below! 

Gas Exchange By Surface Agitation 

As we discussed above, still water holds less oxygen. Therefore, the water’s surface must be constantly agitated because that’s where the gas exchange occurs. 

If there’s no surface agitation, gas exchange cannot take place. As a result, the oxygen sitting on the surface of the water will not be able to make its way down, and excess carbon dioxide trapped at the bottom cannot find its way out.

Filter does cause surface agitation to an extent, but it may not be enough. The constant flow of bubbles created from an air pump will push the carbon dioxide to the surface and create a favorable environment for gas exchange. 

Increased Oxygen Level 

The top benefit of increased surface agitation with an air pump is that it increases the water’s oxygen level. So what I do is use an air pump with an air stone, and together they create thousands of tiny oxygen bubbles in the water. 

You already know why oxygen is essential for your fish. But do you know plants also require oxygen to sustain themselves? When the night falls, plants release carbon dioxide and take in oxygen. 

Simply put, the higher the oxygen level, the healthier the aquarium will be. 

Enhanced Aesthetics

An air pump definitely helps to add an extra flair to your tank. Have you ever paused and marveled at a beautiful aquarium? Chances are that it had some sort of air pump decoration creating the bubbles in the background. 

There are several ornaments that you can add to work with an air pump and create beautiful bubbles. These ornaments come as treasure chests, fake corals, and even volcanoes! 

I can watch the bubbles coming out of a tiny treasure chest in my 55-gallon tank all day long. 

Useful For Sponge Filter 

If you plan to use a sponge filter in the fish tank for the obvious benefits, you might also be interested in getting an air pump since these filters don’t have a motor of their own. 

Sponge filters rely on the upward thrust provided by an air pump to drive the water through the sponges. 

Sponge filters are small, inexpensive, quiet, and serve as a hotbed for beneficial bacteria. If you plan to breed fish, you must get a sponge filter, so the tiny eggs and fry aren’t sucked in. 

How To Aerate Aquarium Water Without An Air Pump?

If you’ve decided not to buy an air pump, there are a couple of tricks you can pull to aerate the tank. But first, it’s important to know the difference between aeration and oxygenation. These two words are used synonymously, but they mean entirely different things. 

Oxygenation simply refers to how much oxygen is dissolved in the water. On the other hand, aeration is the amount of oxygenated water moving around in the tank.

Aeration depends on the movement of water throughout the tank. 

So, what does an oxygenator do? It adds more oxygen to the water, but the oxygen doesn’t disperse well due to a weak flow rate. 

On the other hand, an aerator produces oxygen while also creating a strong water flow. 

Now that you know the difference between aeration and oxygenation, let’s look at how you can aerate aquarium water without a pump.

Cup Method 

The simplest way to aerate water in a fish tank without a pump is to use a cup or pitcher. Just fill the cup or pitcher with aquarium water, lift it high, and pour the water back into the tank. On the way down, the water will pick up oxygen. 

Make sure to lift the pitcher as high as possible so that it picks up more oxygen along the way. This will also ensure that the water will travel to the depths of the tank. 

While pouring the water, be careful not to stir the substrate too much. 

Powerful Filter 

The filter you use in your aquarium also makes a big difference. If you don’t want to add a pump anytime soon, the filter will have to fill in the shoes. It’s going to be the primary source of oxygenation and aeration for the tank. 

A powerful filter will generate enough surface agitation and water movement to generate and retain oxygen. And for a filter to work effectively, it shouldn’t be dirty or clogged. 

Spray Bar And Waterfall Filters

A spray bar or a trickle filter can also help you achieve good water aeration. As the water comes down off the spray bar or waterfall filter, it will pick up oxygen on the way down. 

Even better, since the water flows down from a certain height, it will propel the water into the tank – creating a well-aerated environment. 

Live Plants 

Adding more plants to the tank is another surefire way of ensuring enough oxygenation and aeration. Plants photosynthesize to live – it’s a process by which plants use light to synthesize nutrients from carbon dioxide and water – producing oxygen as a byproduct. 

However, bear in mind that the opposite of photosynthesis happens when the lights go off. So if you keep the lights out too much, the plants will use up oxygen excessively. 

New Fish 

Adding fish sounds ironic since an overpopulated tank directly translates to depleted oxygen levels. But hear me out.

If you add active and fast-moving fish to the water, their movement will help to stir the water – moving oxygen-rich water from the top to the depths. 

Final Words: How Long Can A Fish Live Without An Air Pump

This question is kind of rhetorical, and the answer may sound vague. The answer depends on many things. 

If the tank is well oxygenated and aerated even in the absence of an air pump, the fish can live their entire lives without ever needing an air pump. 

However, if the tank is too small to begin with, overpopulated, and the water is still, it won’t take long for fish to suffocate and die. 

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