do angelfish get fat?

Why Is My Angelfish So Fat?

Freshwater angelfish are known for their slender appearance. Even a perfectly healthy, well-fed angelfish will remain thin and lean. Because of this, if your fish gains weight, you should notice it immediately. Fat angelfish have a slight bulge in their stomach that makes them look wider at the bottom. If your pet angelfish seems rounder than usual, it’s common to wonder what’s wrong with it.

Angelfish can get fat due to egg carrying, illness, tumors, overeating, and poor water conditions. Angelfish are also prone to intestinal parasites that cause their guts to expand. You can narrow down exactly what’s happening through a process of elimination. A fat angelfish is never a good thing, unless she’s pregnant.

Some issues impact the health of your fish more severely than others. In the best case, your fish may be about to lay eggs. In the worst, it could have an untreatable condition that will prove lethal. Be sure to observe your fish’s behavior, swimming patterns, and daily routine to tell the difference.

Do Angelfish Get Fat?

When angelfish get fat, the only visible change is in their stomach, right where the fins are. That area becomes swollen and round, almost as if the fish swallowed a marble.

There are many reasons why this could happen. Some are a major cause for concern, while others are reason for celebration. Either way, you can determine why an angelfish got fat by:

  • Keeping a close eye on how it behaves
  • Monitoring how you care for it

It will be very difficult to know the reason just by looking at the swelling alone. Let’s explore the most common reasons why angelfish gain weight:


The cause of your angelfish’s round belly could be pregnancy. It’s worth noting that angelfish don’t get pregnant in the traditional sense of the word. Female angelfish don’t carry live young in their belly.

Instead, a female will carry unfertilized eggs, which she then releases in a predetermined corner of the tank. The male then proceeds to fertilize the eggs in a process that lasts about 2 hours.

Be aware that female angelfish will produce eggs whether they are near a male angelfish or not. If you have a lone angelfish in a tank and it looks bloated, don’t worry. It could just be a female carrying eggs that will never be fertilized.

How to Tell If Your Angelfish Is Pregnant

The first sign that your angelfish is pregnant appears before the belly even expands. You can identify angelfish that are carrying eggs through the following behaviors and physical changes:


Pregnant angelfish don’t spend too much time swimming around. They swim slowly and take it easy for most of the day. They’ll usually stay in one part of the tank.

Pairing Up

Angelfish are monogamous. The males are very involved with their children from:

  • The moment the female produces eggs
  • Up until the fry (baby angelfish) are able to swim on their own.

Paired angelfish will often protect and keep each other company. If the fat angelfish in your tank is seen spending a lot of time with another fish, they are most likely mated.

Nest Cleaning

Paired angelfish will spend 1 to 2 days cleaning out the area where the female will lay the eggs.

Protruding Papilla

Pregnant angelfish have a very small tube, usually red or black in color, that protrudes from their stomach. It might be hard to see, especially since female angelfish have a flatter papilla than male angelfish. If you see it, you’ll know that you can expect baby angelfish soon.

is my fish fat or pregnant?


Most issues regarding swollen bellies in angelfish can be fixed by making a few changes. However, that’s not the case with tumors. According to a study from the University of Florida, fish tumors are mainly caused by retroviruses. These are viruses that copy themselves as a part of a cell’s DNA. It does this by:

  • Taking a cell’s DNA
  • Reverse transcribing it back into RNA
  • Then, when the RNA is converted back to DNA, the virus will have already implanted itself into the code

Because the retrovirus’s sequence changes so often, it is very difficult to treat a tumor caused by retroviruses. Unfortunately, most fish with tumors cannot be cured.

How to Tell If Your Angelfish Has a Tumor

At a glance, it may be hard to identify a tumor in your fish. However, you can look for these signs:

Change In Appetite

Tumors in the gut of an angelfish interfere with the fish’s digestion. A fish with a tumor will slowly lose appetite. This is what causes the deterioration and eventual death of the fish.

Getting Attacked By Other Fish

Fish are highly opportunistic, a trait that sometimes leads them to cannibalism. Even when properly fed, they may still take any chance they can to feast on other fish. When a fish in the tank is weak and unable to defend itself, the other fish might try to take advantage and eat it.

Bumps In Other Locations

Try to spot other tumors growing from the fish’s body. In particular, these should appear on the:

  • Mouth
  • Gills
  • Fins
Severe Protruding Of Scales

When an angelfish is overfed or carrying eggs, their stomach expands visibly. Most of the time, however, their stomach doesn’t expand to the point that the scales are affected. That’s not the case with tumors.

Are the scales on and around the enlarged belly altered and lifted? This is usually caused by severe infection or a tumor.


As mentioned, fish are opportunistic and survival is always on their mind. Even after eating, they will crowd around flakes you drop into the water. That makes it very easy to overfeed a fish.

However, an angelfish’s body may not swell from the food itself. Instead, swelling will result from the constipation that overeating causes. Angelfish are more likely to suffer from overfeeding because of their lean bodies.

How to Tell If Your Angelfish is Overfed

You can check for these signs:


This might be the most difficult behavior to observe. That’s especially true if you have more than one fish in the tank.

However, if your angelfish is overfed, one of the consequences is being unable to poop.

Seeing Fish Food At The Bottom Of The Tank

Any excess food that your fish can’t eat within 2 minutes will sink to the bottom of the tank and begin to decompose. No matter how hungry they are, fish will ignore that rotten food.

Gasping For Air

When fish food begins rotting at the bottom of the tank, it messes with the chemistry in the water. It often causes oxygen levels to go down. When this happens, fish will swim up to the surface of the water and gasp for air.

Dirty Water

If the water gets dirty no matter how often you change it, it’s possible all the uneaten food is the cause.


According to a study from the Department of Fisheries and Aquaculture in Gainesville, Florida, angelfish are prone to many types of intestinal parasites. Among the most common are:

  • Hexamita
  • Capillaria
  • Myxosporidians
  • Eurystrongylus
  • Coccidia

Aside from bacteria, these diseases are also caused by the angelfish experiencing changes in:

  • Water
  • Diets
  • Temperature

How to Know Your Angelfish Has a Disease

While that seems like a wide range of possible diseases, don’t worry. There are ways for you to identify these problems.

Unusual Swimming Patterns

Sick fish aren’t in full control of their bodies. When infected, they begin:

  • Swimming sideways
  • Twisting around
  • Curling into themselves

As such, an angelfish with an unusual swimming pattern is one that definitely needs treatment.

Loss Of Appetite

Parasites make us humans feel like anything we eat will hurt us. The same thing happens with fish. What if you no longer see your fat angelfish race to the surface to get some grub when it’s lunch time? Then you should be concerned.

Skin Discoloration

Angelfish change the color of their scales when they are:

  • Stressed
  • Sense light changes in the environment

However, a bloated belly coupled with skin discoloration could lead to trouble. Parasites usually cause the skin on angelfish to either darken or become lighter.

Severely Protruding Scales

Besides skin discoloration, parasites also change the way angelfish scales function. Fish have scales for protection against germs and water friction. However, if a fish is already affected with a parasite, the scales will lift up and protrude from the fish. This weakens their defense system.

What To Do If My Angelfish Has Big Stomach?

After identifying what could be wrong with your angelfish, the next logical step is treatment. Depending on the health issue your fish has, you can either resolve the problem on your own or take it to a vet.

Even when pregnant, there is always something you can do to make sure your fish is comfortable. Let’s explore ways you can help the fish transition healthily from bloated to slim again.


Is your fish expecting? Then you can:

Refrain From Changing The Water Too Frequently

Angelfish get very stressed from changes in the water. This may include:

  • Temperature
  • pH
  • Ammonia levels
  • Oxygen

Unless you absolutely have to, try not to change the water too often.

Separate The Other Fish

Angelfish get very aggressive when pregnant. Consider separating the angelfish pair from the other fish.

Angelfish don’t like being moved around too much. That’s especially true if they’ve already chosen a spot where the mother will lay her eggs. As such, if you can, move the other fish into a separate tank and leave the pair alone.

Don’t Add New Fish In The Tank

As mentioned, pregnant fish get aggressive. Adding new tank mates will only raise a pregnant angelfish’s stress levels.

Make Sure She Gets Enough To Eat

Pregnant angelfish are riddled with lethargy. This means the female won’t be as fast as the others when it’s time to eat. She might not get enough food due to her lack of speed.

angelfish has big stomach


Tumors in fish are challenging to treat. There aren’t many drugs or remedies that can cure them. Most gut surgeries aren’t successful, usually due to the placement of the tumor.

The most successful tumor remedies for fish are those that appear on the fins. Those can be treated with special medicated water. The gut is a different story.

Still, even if you manage to diagnose your fish with some kind of gut tumor, it’s best to let a vet confirm it. This will be done with an ultrasound and the expert can explain how to proceed from there.


Is your angelfish getting fat because of food? Then you should:

Have A Schedule

A schedule will allow for more organization when it comes to the healthy habits of your fish. This will include when you feed the fish, when you dim the lights, when you change water, and so on.

Feed The Proper Amount

Young angelfish eat 4 to 5 times a day. Adult angelfish eat 2 to 3 times a day. Some people make the mistake of feeding based on the size of the tank. However, you should measure how much food to give based on the number of fish in the tank.

Change The Other Fish

Not all fish require the same amounts of food per day. If your angelfish are in a community tank with different species, consider separating the big eaters from the angelfish.

Treat The Constipation

Treat the constipation by using a bit of castor oil and Epsom salt. You can also change the regular fish food with a kind that contains more fiber.


If you’re dealing with an angelfish disease, then you can:

Check The Quality Of The Water

Change out the water if it looks dirty or hasn’t been cleaned in a long time. The water should be changed every 2 to 4 weeks, depending on how many fish are in the tank.

Eliminate Stress

Stress can cause your angelfish to become ill. If your angelfish is in a community tank, make sure the tank mates are most compatible with them.

Likewise, the tank should be in a place where there aren’t too many people passing by. Lights shouldn’t be switched on or off. Constant movement and light changes will stress them out.

Treatment for pathogens infecting your fish will differ depending on the disease. It’s always best to consult a vet to figure out the best treatment for your angelfish.

On the whole, your angelfish shouldn’t be fat unless it’s pregnant. If you find it is, then be sure to take action.