Why Does My Catfish Stay At The Top Of The Tank? (With Solutions)

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When I saw my friend’s new fish tank, I couldn’t help but notice that the catfish was always floating at the surface of the water. Luckily, I saw this behavior earlier in my tank, so I knew what might cause that and how to overcome it.

Catfish tend to stay at the top of the tank due to oxygen deficiencies, secondary to high temperature to stagnant water. However, some catfish will occupy the upper sections due to elevated ammonia concentrations, or a swim bladder disorder, compromising the fish’s buoyancy.

As we move forward, I will show you some practical steps to deal with a catfish that always swims to the top. I will also share some tips to help you understand whether this is normal behavior or if an underlying condition is involved.

Why Does My Catfish Stay At The Top Of The Tank?

Catfish that spend a lot of time at the top cause many concerns because they are bottom dwellers. This is why aquarists are encouraged to give them at least two inches of gravel. 

You don’t expect these creatures to spend so much time at the top, not unless external factors such as the following are driving them to do so:

1. Some Catfish Prefer The Top

You cannot ignore the possibility that your catfish is spending a lot of time at the top because it prefers that tank section. Catfish are just as unpredictable as any other aquarium fish. If yours are drawn to the top rather than the bottom, you don’t have to panic.

If their behavior was a sign of distress, you would observe additional symptoms such as lethargy and loss of appetite. But if the catfish are happy and healthy, leave them alone. 

Test the tank for toxins. You can also check the parameters. If everything is fine, you don’t have to take any action. As we proceed, I will show you how to ensure that the water is suitable for your fish.

2. Your Catfish Doesn’t Have Enough Oxygen

Catfish extract the oxygen they need from the water. That oxygen enters the tank through the surface. I suggest getting strong filters and pumps to distribute the oxygen evenly.

You must also maintain appropriate temperatures. This is because hot water holds less oxygen than cool water. High temperatures lower the oxygen levels in the water. Stagnant water is also problematic. Stagnation allows oxygen-deficient pockets to form in the tank. 

Because oxygen enters the tank through the surface, catfish in an oxygen-deficient aquarium will rush to the top, where the oxygen levels are much higher.[1] 

They will stay at the top until the situation below improves. Catfish that have been starved of oxygen will become more sluggish over time. Besides swimming at the top, they will also gasp for air.

It should be noted that stagnation and high temperatures are not the only potential causes of oxygen deficiencies in aquariums. You can achieve similar results by overstocking your tank.[2]

Aquariums have finite space. They have a limit to the volume of oxygen they can hold. A large population of cory catfish will consume the oxygen in the water faster than the tank can replenish it.

Keep this in mind before you add more catfish to the aquarium. But you shouldn’t be so quick to sell your excess catfish. First, make sure you have an oxygen deficiency.

Symptoms like gasping and lethargy that people associate with oxygen deficiencies have other sources. If you have the money, buy a portable dissolved oxygen meter.[3] You can test the tank by placing the meter’s probes in the water and recording the readings on its display.

If you prefer a more financially friendly method, buy some chemical test kits. You can take action once you’ve definitively determined that you have an oxygen deficiency.

3. The Water Conditions Are Not Suitable For Catfish

A tank with poor conditions will send the catfish to the top. This is because they want to escape the poor-quality water in the tank, but they have nowhere to go but up. Keep an eye on the following:

  • Inappropriate Water Parameters

The parameters are essential. Every fish has a range within which it thrives with regard to pH, temperature, and hardness. The wrong temperature can attract stress and disease. The same is true for a pH that is constantly changing.

Diseased and stressed catfish can manifest all kinds of odd habits. That includes lying still at the bottom, swimming around haphazardly, or frequenting the top. 

  • Elevated Ammonia

Fish hate ammonia. It burns them. But tanks cannot avoid ammonia. It forms when leftovers and fish waste rot.[4] Fish will also exhale it from their gills. High concentrations of ammonia will harm cory catfish, compelling them to look for a way out of the tank.

Because they cannot leave, they will settle for gasping at the surface. Ammonia is dangerous because it can destroy a catfish’s gills, causing labored breathing. The clear substance has the power to kill fish if it goes unchecked. 

  • Excessive Water Changes

You have to change the water regularly to keep the tank clean. The absence of water changes encourages ammonia levels to spike, which you do not want. That being said, water changes can do more harm than good if they are too large and too frequent.

Catfish are hardy creatures. However, like other fish, they crave stability. To a fish, a sudden temperature change is just as uncomfortable as a temperature that is too high or too low. Significant and frequent water changes can induce stress in catfish because they alter the chemistry of the water.

They are particularly problematic in tanks with new catfish. If a catfish is still struggling to acclimate to life in a new tank, significant water changes will push it over the edge, causing the creature to manifest various signs of stress. That includes hanging out at the top.

4. The Catfish Suffers From A Swim Bladder Disease

Infections and diseases can drive catfish to the surface because of the distress they cause. Swim bladder disease is the most common of all the illnesses you should look for in situations like this.

Swim bladder disease always comes to mind in such cases because the swim bladder allows catfish to control their buoyancy.[5]

The catfish’s ability to swim will suffer if the swim bladder is compromised by infections, toxins, and a poor diet. It may float uncontrollably to the surface. It could also drift into an upside-down position.

How To Treat Catfish That Stay at the Top?

Catfish are peaceful, easygoing, adaptable creatures, and it doesn’t take much to keep them happy. That is all you have to do to treat catfish that stay at the top. Keep them happy. These are just a few of the tactics you can use:

1. Adjust The Water Parameters

I highly suggest that you maintain the proper parameters, including a pH of 7.0 to 7.8 and a temperature of 72 to 78 degrees. Keep these parameters stable. Do not permit the pH and temperature to change dramatically. 

This is why it is vital to install a heater rather than relying on the ambient temperature.

You should also buy all the tools you need to lower (peat moss, driftwood, Catappa leaves) or raise (limestone, shells, coral sands, gravel) the pH just in case.

It is also essential that the ammonia and nitrites remain at 0 ppm while nitrates are below 20 ppm. To measure those, I use the API Water Master Test Kit (link to Amazon). That bundle is highly cost-effective and provides accurate measurements within minutes.

2. Get Rid Of Toxins

If the toxins in your tank are wreaking havoc on your catfish, you have three options:

  • Water change

Start by performing a 50 percent water change. This will lower the ammonia concentration immediately. You should also look for and remove any rotting elements in the tank.

  • Water Conditioners

If you cannot perform a large water change for one reason or another, add a water conditioner like Seachem Prime (link to Amazon). It works in minutes. If you are new to this, here is an article where I discussed how much water conditioner you should use in your tank

Water conditioners can neutralize everything from ammonia to chlorine and chloramine. They also work to prevent ammonia spikes or toxin elevations in the future.

  • Water Source

I highly recommend testing your water source. Many countries treat tap water with chlorine and chloramine, which fish hate.[6] Wellwater isn’t necessarily better because, in some cases, it has nitrates and bacteria from agriculture runoff. 

Bottled water goes through thorough filtration processes that remove minerals which your catfish need. Rainwater has a low mineral content, and you cannot predict its pH. Distilled water is often stripped of magnesium, sodium, and other valuable minerals. 

Investigating the water source will give you an idea of the water conditioners you need to treat that water to make it suitable for your catfish. You can easily do that with the 17 in 1 Premium Drinking Water Test Kit (link to Amazon).

3. Enrich The Water With Oxygen

If you have an oxygen deficiency, you can use one or more of the following steps to alleviate the discomfort of your catfish:[7]

  • Pour water into the tank from a great height. First, this disturbs the water. Secondly, the water picks up oxygen as it falls through the air.
  • Perform a 50 percent water change. The new water will introduce oxygen to the tank 
  • Install HOB filters and air pumps. You can also use a spray bar.
  • Shut the lights off during the summer.
  • If the water is too hot, you can add ice cubes in a zip-closed bag during emergencies.
  • You can also use a fan to blow across the surface. This will lower the temperature. Don’t forget to remove the tank cover.
  • Add an airstone to create aeration. I personally use the Hygger Aquarium Air Stone (link to Amazon). That kit is incredibly quiet and gets the job done. All you need to do is to place it in the middle of your tank. 

4. Treat Swim Bladder Disease

Swim bladder disease can be treated in several ways:[8]

  • Maintain a clean tank with the correct parameters.
  • If the catfish is bloated, starve it for three days. Place it on a diet that includes cooked and peeled peas on the fourth day.
  • Raise the temperature to 80 degrees F.
  • Catfish with infections should be quarantined where necessary and treated with broad-spectrum antibiotics.

How Can You Tell If a Catfish Is Stressed?

Catfish cannot hide their stress, not completely. If you can see these symptoms, in the absence of other explanations, you have every reason to assume that the creatures are stressed:

1. Your Catfish Will Remain Inactive

Stressed catfish are either lethargic or completely inactive. Sometimes they will lie listlessly at the bottom. They may even appear dead.

2. The Catfish Will Gasp For Air

People think that gasping always proves that a tank is oxygen deficient. But that isn’t always the case. Believe it or not, stressed catfish can also gasp at the surface.

3. Your Catfish Won’t Be Interested In Food

Stressed catfish will stop eating. You may assume, initially, that you overfed the creatures because their tank is filled with so many leftovers. But if you observe them, you will notice that they have stopped eating.

4. The Catfish Will Change Its Swimming Patterns

Some stressed catfish will stop moving. Others will do the opposite; their swimming patterns will become erratic. That includes crashing into objects and surfing the glass. 

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If your catfish is staying at the top of the tank, your first step should be to look for an air stone. There may be one that you forgot about, or it may be defective. If the catfish has a bloated belly and is crashing into objects, you probably deal with a swim bladder disorder. In this case, follow the steps mentioned above.

Next, check the parameters in the tank. Make sure that the ammonia and pH are within the proper range. After that, check the water source. You may also need to do a 50 percent water change or treat the water with a water conditioner.


  1. https://k945.com/why-are-these-catfish-swimming-at-the-top-of-the-water-in-benton-video/
  2. https://www.petco.com/content/petco/PetcoStore/en_US/pet-services/resource-center/health-wellness/why-is-my-fish-breathing-at-the-surface.html
  3. https://www.cuteness.com/article/test-aquarium-water-oxygen-levels
  4. https://www.swelluk.com/blog/why-are-my-fish-swimming-at-the-top-of-the-tank/
  5. https://www.kqed.org/science/1922038/the-mystery-of-the-upside-down-catfish
  6. https://longsecowater.com/blog/the-best-water-for-your-aquarium
  7. https://aquagoodness.com/how-to-increase-oxygen-in-fish-tank/
  8. https://www.thesprucepets.com/swim-bladder-disorder-in-aquarium-fish-1381230