Is Too Much Oxygen Bad For Aquarium Fish?

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Depletion of oxygen in the aquarium is a real nightmare. Insufficient oxygen can make the fish suffocate and die in the tank. But have you ever sat back and thought about the high level of oxygen in the tank? If a low level of oxygen can bring so many consequences, there might be some side effects of a high level of oxygen. Or is too much oxygen even a thing in the aquarium? And if it, is too much oxygen bad for your aquarium fish?

Yes, too much oxygen is harmful to your fish, and most of the time your fish will develop fatal yet treatable gas bubble disease. Nothing is good when taken more than necessary.

This is just a layer of information and I know you want to go deeper into this. So, here is an article entirely dedicated to the what, why, how, when related to too much oxygen in an aquarium.

Is Too Much Oxygen Bad For Aquarium Fish?

Well, to be honest, too much oxygen in an aquarium is rarely a case. But if you use direct oxygen in the tank during an emergency situation then there can be a supersaturated level of oxygen in the tank.

Water can hold only a certain level of oxygen till it gets fully saturated. When the water reaches its level of oxygen saturation, it will no longer dissolve any oxygen.

And this level of oxygen is okay and harmless to fish and your fish will happily breathe in the water with saturated oxygen.

However, a problem arises when the water starts to get supersaturated with oxygen due to various factors.

Fish will breathe in this super-oxygenated aquarium water and hence the oxygen will leach out inside the fish.

The leaking of oxygen in the bloodstream of fish will produce bubbles, gas bubbles to be precise, in the tissues.

This production of bubbles in the gills, eyes, and fins of fish is called gas bubble diseases. And trust me it is painful as hell.

A high level of nitrogen is generally the reason why your fish is suffering from gas bubble disease. But there is a slim chance that it is due to a high level of oxygen level.

So, yes too much oxygen is actually bad for your aquarium fish and you have to take measures to level the oxygen.

You might like to read a full article on How To Maintain The Oxygen Level In Aquarium?

What Causes The Increment Of Too Much Oxygen In The Aquarium?

Oxygen will not decide itself to multiply in the tank as bacteria does. Actually, as a matter of fact, it cannot multiply like that.

So, there are external factors that will supply oxygen into the tank more than is necessary.

Believe me, there is something seriously wrong with your tank because too much oxygen or supersaturation of oxygen is one of the rarest things to happen in the tank.

  1. The increment of the pressure due to the leakage in the water pipe or the captivating pump will result in the oversaturation of oxygen as an excess level of oxygen will dissolve in water.
  2. Rapid heating of the water in the aquarium leading to fast temperature change will trap a high level of oxygen as cold water holds a high level of oxygen compared to warm water.
  3. Direct supply of oxygen to the tank during emergency situations like depletion of oxygen, fish gasping to catch a breath, etc.

How To Know There Is Too Much Oxygen For The Fish In The Aquarium?

Knowing the level of oxygen in the tank is quite important as knowing the level of ammonia, nitrite, and nitrate.

You might like to read more about Ammonia Poisoning in Fish Tank | How to Get Rid of It

So, you need to stay informed and the way to stay informed is quite easier than you thought.

Here are few ways to if the water contains too much oxygen in the aquarium.

  1. Use a portable dissolved oxygen meter regularly. This will indicate if the level rises up any day.
  2. You will see small bubbles present in the fish and decorations present in the tank.

How To Cure Gas Bubble Disease Caused By Too Much Oxygen In The Aquarium?

First of all, you need to find the root cause of the problem and try to solve it from there. But sometimes it can be too late before you lower the oxygen level of the tank.

However, eliminating the prime reasons can stop the disease from getting worse. Secondly, make sure to attend to all the aquatic beings that are affected by too much oxygen in the tank.

Now, let’s talk about the treatment of gas bubble disease in the fish:

  1. Your vet can remove the bubbles with the help of needles and syringes by articulating them one by one.
  2. Experts and experienced aquarists are known to use barometric chambers to cure gas bubble disease.
  3. There are few antibiotics that can help your fish cope and get over gas bubble disease. Ask your veterinarian for a prescription for antibiotic therapy.

How To Prevent Too Much Oxygen In The Aquarium?

Well, prevention is better than cure so following this motto let’s make sure we don’t let the oxygen level get past the saturation point.

If you maintain simple things in the tank, you will end up having an oxygen level well-maintained as well.

Not only the oxygen level, but good maintenance of aquarium also make sure the removal of toxic chemicals and harmful microorganisms.

Okay, now coming back to the point, here are things you can do to prevent the build-up of too much oxygen in an aquarium:

  1. Check the plumbing and filtration components. Look for the leakage and damage and solve or remove the damaged items immediately.
  2. Keep note of the water level in the tank so you can notice the water leakage with the decrease in the level of water. This way you will be one step ahead to solve the problem.
  3. Check the temperature of the new water during the aquarium water change and make sure to maintain the tank temperature constant during the process. Learn more about Is Too Much Water Change Harmful For Your Fish: How To Do It Safely
  4. Do not let the temperature increase rapidly or fluctuate more often.
  5. Remove the faulty heater if you start having trouble maintaining the ideal temperature. Learn more about Freshwater Aquarium Equipment Checklist : Aquarium Supplies You Need.

Frequently Asked Questions

I know fishkeeping can bring never-ending questions and it can be stressful. So, to relieve you from a few of the questions by answering here.

How To Tell If My Fish Needs More Oxygen In The Aquarium?

Your fish will tell you when they will need a little more oxygen in the tank. All you have to do is look at fish behavior properly.

  1. Fish gasping at the surface of the tank
  2. Less activity of fish and lethargy in them
  3. Loss of appetite in fish
  4. Breathing difficulty in fish

Does A Filter Provide Oxygen For A Fish Tank?

Yes, apparently the water flow rate due to the filter causes surface agitation in the tank. This surface agitation helps during the oxygen exchange and hence the oxygen supply is maintained in the aquarium.

You might like to read an article on Aquarium Filtration Methods.

How Do I Check The Oxygen Level In My Fish Tank?

Well, it is quite easy to test the oxygen level in the fish tank if you are well-equipped. You need to get a portable yet cheap as well as efficient dissolved oxygen meter.

You can put a probe after calibrating the dissolved oxygen meter in the aquarium water and wait for a while.

Once the meter shows the reading, read the level of oxygen from the digital display in the meter.

Extech DO210 Dissolved Oxygen Meter and RCYAGO Portable Dissolved Oxygen and Temperature Meter are best dissolved oxygen meter. I highly recommend you to get one of these.


In a nutshell, nothing is good when the limit is crossed. You need to maintain the oxygen in the tank to the ideal level. If you mess up or mistakenly fluctuate the temperature in the aquarium, immediately test the oxygen level and adjust the temperature back to normal. Be careful while increasing the oxygen level in the tank. Overdoing and carelessness will result in diseases and health hazards to fish as well as other aquatic living beings in the tank.

Stay alert and careful while taking care of your fish. Keep checking the leakage in the water and do not overlook the problems that might result in hazards in long run.

You will do good and I will be here to help. If something comes up or things go sour in the tank, drop a comment below and I will get back to you as soon as possible.

Good luck!!

Happy Fishkeeping!!!

Recommended Articles:

  1. Most Common Beginner Aquarium Mistakes When Setting Up New Tank
  2. How to Acclimate Fish
  3. Beneficial Bacteria In The Aquarium: What Are They And Is It Essential?

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