Why Is My Angelfish Swimming Upside Down?

If your angelfish is swimming upside down in the aquarium, it is most likely is that it is suffering from bladder disease. Other possible causes include injuries, overfeeding, constipation, bacterial or parasitic infections, or issues with the water.

An angelfish that floats upside down is not always a serious condition and can often be cured. If your Angelfish is swimming upside down, you should first move it across into a medical tank where it is isolated, which removes some of the possible causes, and where it may automatically recover.

The Reasons Why An Angelfish Is Swimming Upside Down

There are several reasons which may be the cause of an angelfish swimming upside down.

The possible causes are discussed in this article.

Check Your Angelfish For Bladder Disease

An angelfish swimming upside down is most likely caused by an issue with its swim bladder, and a diagnosis will generally be bladder disease.

Signs that the angelfish has an infection are that it will exhibit the following symptoms.

  1. It will exhibit clamped fin.
  2. It will shake.
  3. It will lose its appetite.
  4. All the other symptoms are associated with a swimbladder disorder.

Bladder disease is not generally lethal, but it is a pointer to a more serious problem. The first action is to move the Angelfish out of the main tank and into a correctly prepared isolation tank.

It will reduce bacteria levels and, in many instances, will be sufficient to kill the problem bacteria causing the infection.

Unfortunately, the only way to confirm a bacterial infection is by sticking a needle directly into the bladder and testing the fluid for the type of bacteria, which is beyond the skills of most aquarium owners.

Ensure that your water parameters are healthy; it is a good idea to try using a broad-spectrum antibiotic for the fish.

Parasitic worms can also infect aquarium fish, but this is rare.

Dark Angelfish

Check Your Angelfish For Injuries Or Deformities

Next, check for physical issues such as.

  1. Try to check the fish over for any birth defects or physical abnormalities and ensure that everything looks normal (other than the way it is swimming.)
  2. Check for injuries, particularly if the angel fish was not alone
  3. Check for any tumors that could be suppressing the swim bladder.

If any of these inspections reveal a problem, you will have to decide to either humanely euthanize the angel fish or allow it to carry on living.

It must be said, however, that many Angelfish will live for a long time with this condition. Whatever you decide, it is important to ensure that it is not suffering.

Check Your Angelfish For Air Bloat

Air bloat is a common cause of swim bladder problems in Angelfish.

Have you ever watched the Angelfish eating, and did it seem to gulp air at the surface?

It is not normally an issue and is a tactic used to help the fish maintain buoyancy while eating the food at the surface.

If too much food has been dropped into the tank, one of the possible consequences is that it will continue to suck up the air as part of the behavior air and so will end up with a problem.

It introduces unwanted air into the fish’s stomach. Flake food that floats at the water’s surface encourages gulping of air. Since too much air in the belly of a fish can end up in its swim bladder.

To prevent the fish from gulping too much air, feed them pellets that sink to the aquarium’s bottom and are consumed there.

Your Angelfish May Be Overfed

Fish do not have any controls against overeating, and neither do they have a concept of overeating.

It means that they will continue to eat even after they have received sufficient nutrition.

Too much food can result in a bloated belly, which presses against the swim bladder. Only feed your fish one pinch of food per day, however tempting it may be to “spoil” them. The fish should be slightly underfed instead of overfed.

The Angelfish May Have Constipation

If the fish is constipated, the fish’s stomach will press against the swim bladder and cause the fish to lose buoyancy control and possibly swim upside down.

Many people recommend serving angel fish peas to help get the angel fish’s digestive system moving. To do this, prepare the pees by peeling and chopping fresh peas or defrosting frozen peas in Lukewarm water.

Cut a small slit in the pea’s skin and squeeze until it pops out of the skin and into the water. If you boil the pees, they will sink to the bottom of the tank.

Don’t feed frozen peas to the angel fish because as it thaws, it increases in volume, which won’t be great news for the fish if the thawing food is inside the stomach.

Feed your fish high-fiber foods once a week. It could be a pea or any other cooked fiber-rich vegetable your fish is willing to eat.

One of the benefits of an isolation tank is that you can completely control the amount of food the fish consumes.

Don’t feed the fish anything except for a pea for the first twenty-four to forty-eight hours. This period will allow the fibers in the pea to help start up the Angelfish’s digestion.

Remove all excess food from the tank because rotting food can cause a sudden ammonia spike which is not optimum for a tank designed to treat the fish.

If the fish is constipated, the outcome of these measures is that the stomach starts to lose volume, relieving pressure on the swim bladder and allowing it to function properly.

Watch for your fish producing waste and watch the action. It should leave the body and hang from its rear for a couple of seconds, not continue to be attached.

Always ensure that you keep the tank at the correct water temperature.

The Water Temperature May Be Wrong For Your Angelfish

Fish are cold-blooded creatures, and their metabolism optimally depends on the body’s temperature.

As the water temperature reduces, the angelfish’s metabolism slows, marginalizing its ability to digest food properly.

The Water Quality May Be Bad For Your Angelfish

Dirty water can cause bacterial infections.

Changing the water in accordance with a regular schedule keeps the nitrates in the aquarium in check, preventing potential bladder infections.

Always use a suitably sized filter (the larger, the better) because it will enable the tank to house more beneficial bacteria.

The more bacteria, the stronger the biological filtration, lowering the chance of bladder infection.


A problem with the angelfish swim bladder will be making it swim upside. This mechanism is situated in the lower half of the fish’s body and is used to control buoyancy.

A problem is often caused by a simple factor such as overfeeding or constipation, in which case a small fast or increasing fiber intake will resolve the problem.