Angelfish Staying At The Top Of The Tank: Reasons & Solutions

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I got worried as I saw my angelfish swimming at the top for extended periods. I was afraid it might have swim bladder disease, but I wasn’t sure. As months passed, I learned that this phenomenon could actually be related to several conditions. Luckily, there are ways to bring things back to normal.

Angelfish typically stay at the top due to a swim bladder disease compromising the fish’s buoyancy. Angelfish suffering from this condition may also swim vertically, head up or upside down. However, angelfish also stay at the top because of oxygen deficiencies, ammonia spikes, and bullies.

As we move forward, I will take you step-by-step through the process of treating angelfish that frequently swim at the top of the tank. That includes an excellent video that illustrates how to treat a swim bladder disease, which is most frequently the case.

Also Read: Stress In Angelfish

Why Is My Angelfish Swimming At The Top?

Maybe the angelfish prefer the top of the tank. You never know. Fish are just like humans. They don’t have the same personalities. Therefore, you cannot rule out the possibility that the angelfish like the top.

However, you can’t reach that conclusion without first investigating the conditions in the tank. Ultimately, aquarists expect angelfish to swim in the middle.[1] 

If yours prefer the top, you have to make sure they are healthy by ruling out some of the negative factors that can compel angelfish to flee to the surface, including:

1. Your Angelfish Share A Tank With Bullies

Beginners don’t expect angelfish to run from a fight because the creatures are aggressive. They are more likely to bully their tankmates. However, angelfish are not the most formidable creatures in the aquarium.

Some fish are larger and more aggressive, including Piranhas, Arowanas (which require 250 gallons of water), African cichlids (which can be incredibly violent), and Oscars (which can grow to a size of 12 inches), to mention but a few.[2]

For the full list of potential tankmates for angelfish, feel free to check this article that I wrote. In there, I listed the best and worst angelfish companions. I also rated each tankmate’s compatibility, ranging from ‘Excellent’ to ‘Terrible’.

Angelfish have long, delicate fins, so they are a target for fin nippers.[3] The fish will also fall prey to larger tankmates. In an aquarium with insufficient hiding spots, they may run to the surface to escape the attention of dangerous tankmates. That is especially true if those bullies are bottom dwellers.

Study the angelfish. Look for signs of violence, such as bruising, lost scales, constant hiding, loss of appetite, etc. Bullied angelfish may stop eating because they don’t want to clash with their tankmates during mealtimes.

2. Your Tank Doesn’t Hold Enough Oxygen 

Various studies have explored the impact of reduced oxygen levels on the behavior of fish. Not only does their breathing become labored, but they will spend more time at the surface because the film of water at the top has the richest oxygen content.

Like humans, angelfish are more than capable of asphyxiating.[4] Stronger angelfish will breathe the oxygen at the surface. But if the oxygen deficiency has weakened the fish, it won’t have the strength to remain at the top. It may eventually sink to the bottom and die.

Some researchers believe that low oxygen environments can enhance a fish’s hypoxia tolerance.[5] But that is more likely to happen in the wild. Fish in prolonged low oxygen settings in an aquarium will most likely suffer long-lasting harm.

Also Read: Angelfish Gasping For Air

3. Your Angelfish Is Carrying A Disease

If your angelfish are sick, their ailment can force them to frequent the top of the tank. You have two primary concerns:

  • Swim Bladder Disease

This is the most common problem. The swim bladder affects a fish’s ability to swim. If the swim bladder’s functions deteriorate, the fish’s ability to move through the water will suffer.

People expect this condition to keep the angelfish at the bottom. They also expect the illness to produce bizarre swimming habits. For instance, the angelfish may swim vertically, upside down, sideways, etc. They do not realize that swim bladder disease can also force a sick angelfish to float at the surface.[6]

The angelfish does not choose to stay at the surface. Because of this condition, it cannot descend to the middle or bottom levels. Swim bladder disease has a variety of causes, including extreme temperatures, bacterial or parasitic infections, ammonia poisoning, high nitrate levels, etc.

  • Gills Infection

Oxygen deficiencies are not always the cause of an angelfish’s decision to remain at the top. Some diseases and infections attack the gills, compromising an angelfish’s breathing.

The fish may rush to the surface in search of the oxygen-rich water at the top. But swimming at the top won’t help because fish absorb oxygen through the gills. And if the gills have been attacked by gill flukes, fungi, and the like, the angelfish cannot breathe efficiently.[7]

4. The Water Conditions Are Bad For Angelfish

Do you clean your tank? Have you taken the time to test the pH levels? What about the temperature? The wrong parameters cause discomfort, especially extreme temperatures.

Angelfish are more likely to rush to the surface to escape a poorly maintained tank with extremely hot or cold water. But the most dangerous of these parameters is the ammonia concentration.

The wrong parameters are problematic because they expose the fish to infections that attack the gills. An angelfish in a poorly maintained tank is also more likely to develop swim bladder disease.

But ammonia spikes are more dangerous because they attack the fish directly, burning the creature’s body, including the gills. 

An angelfish in a tank with a high ammonia concentration will struggle to breathe. It will run to the surface to escape the ammonia’s assault. But because it cannot leave the aquarium, the angelfish will eventually die unless you intervene.

5. Your Angelfish Are Used To Eat From The Top

How do you feed your angelfish? Do you sprinkle the food at the top of the tank? Angelfish are not stupid. They will observe your behavior, and after a while, they will learn to communicate their hunger to you by swimming at the surface.

Some angelfish will swim at the surface at mealtimes because they expect you to add food to the water during this period. 

Others will only manifest this behavior when you fail to feed them. You also have angelfish that demand food at all times, even when they don’t need it. They will swim at the surface until you feed them.

What Should I Do If My Angelfish Stays At The Top?

Fish that stay at the surface should scare you because some of the factors that cause them to float at the top can lead to death. If your angelfish are severely ill or distressed, you can use the following solutions to keep them alive:

1. Improve The Oxygen Levels

Angelfish in an oxygen-deficient tank will lose their appetite. Their breathing will become labored. You can respond with the following solutions:[8]

  • Perform a 50 percent water change. The new water will add oxygen to the tank and produce the necessary agitation.
  • Get a jag and fill it with water from the aquarium. Pour that water back into the aquarium from a great height. The water will collect oxygen as it descends. It will also agitate the tank. Agitation increases the rate at which oxygen dissolves in the water.
  • If oxygen levels are low because of high temperatures, use ice cubes in a zip-close bag to reduce the temperature. You should also de-activate the heater and switch the lights off.
  • Install a more powerful filter, the kind that is strong enough to agitate the water sufficiently.

2. Identify And Treat Potential Diseases

Identify the disease and deploy the relevant solution. For instance, with swim bladder disease, you have to start by performing a water change and cleaning the tank. A clean environment gives the angelfish the best chance of recovering.

If the creature is constipated, place it on a fast for three days before feeding it green pealed, cooked peas.[9] Some people add salt to enhance the creature’s healing rate. Here is an excellent video that will show you how to do that:

3. Improve The Water Quality

These are the ideal water conditions for angelfish:[10]

  • Temperature: 78-84 °F (25-29 °C)
  • pH: 6.8-7.8
  • Water hardness: 3-8 dKH (54-145 ppm)
  • Ammonia & nitrites: 0 ppm
  • Nitrates: <20 ppm

To measure the ammonia, nitrates, nitrites, and pH, I personally use the API Water Test Kit (link to Amazon). That bundle is extremely accurate and brings the results within a few minutes. It also lasts for eight hundred measures, making it highly cost-effective.

When it comes to ammonia, everything above 0.25 may kill your fish. To overcome it, all you have to do is to perform regular water changes. I personally change 15 to 20 percent of the water weekly.

If the ammonia refuses to go down even after a water change, I suggest considering water conditions, such as the Seachem Prime (link to Amazon). If you are new to this, please check this article, where I discussed how to use water conditioners and how much to put from each one.

Here are a few other quick tips that will help you get more suitable water conditions for angelfish:

  • Add sufficient plants and decorations to create hiding spots. Live plants like the amazon sword are better than their artificial counterparts.
  • Add a filter whose strength matches the tank size.
  • Angelfish require at least 20 gallons. Avoid overcrowding by all means.
  • Vacuum the substrate routinely.
  • Check your water source of choice to identify the water’s makeup before using it to perform a water change. You don’t want the water source to add toxins to the tank. Some water sources are better than others.

4. Consider An Automatic Feeder

If your angelfish is swimming at the top because it’s hungry, don’t add food to the aquarium, not unless you keep forgetting to feed the fish. Some aquarists don’t feed their fish on time. 

But if you feed your angelfish twice a day every single day, don’t give it food simply because it has started swimming at the top. You will overfeed the creature, which is terrible because it can cause all manner of illnesses, including swim bladder disease. 

If you can’t remember whether or not you fed your fish, add an automatic feeder. I personally recommend the Zacro Automatic Fish Feeder (link to Amazon). Once you fill it with food and program it, the device will give your angelfish the correct quantity of food at the same time every day. This prevents overfeeding and underfeeding. 

Automatic feeders are perfect for beginners because beginners are more likely to feed angelfish that stay at the top. They don’t yet know that you can’t feed a fish simply because it keeps asking for food.

Why Do Angelfish Stay At The Top After A Water Change?

If you noticed that your angelfish stays at the top, particularly after a water change, you have three primary concerns, namely:

  • Temperature – If the new water is too hot or too cold, it will alter the tank’s temperature. The angelfish will run to the top to escape the extreme temperatures.
  • Toxins – If the new water adds toxins like chlorine and lead, the angelfish will try to escape the poisonous effects of these elements by staying at the top. To check these, you can use the 16 in 1 Drinking Water Test Kit (link to Amazon).
  • Volume – Fish hate drastic changes. They want stable conditions. If the water change is too large, the stress and discomfort will compel the angelfish to run to the top.


Most angelfish swim at the top due to a swim bladder disease. That condition can be treated with the right combination of therapies. The first step would be making a large water change. Then, let your angelfish fast for a couple of days. 

You can feed it peeled peas to lubricate its digestive tract. Then, you need to improve the water quality to provide the angelfish with a healthy balance of water parameters. That includes the temperature, ammonia, nitrates, nitrites, and pH.