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12 Common Angelfish Diseases and Illnesses

12 Common Angelfish Diseases and Illnesses

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This post is written to the author's best knowledge and is not intended to be used in place of veterinary advice. In addition, this post may contain affiliate links. As an Amazon Associate I earn from qualifying purchases.

You likely know that angelfish are among the most popular types of fish that you’ll find in home aquariums. These fish have been popular for decades due to how fantastic they look.

They’re graceful fish that people enjoy observing in their aquariums. It’s great because they’re actually fairly easy to take care of.

The hardy nature of the angelfish makes them a good choice for a beginner. You shouldn’t let that information lull you into complacency, though.

Angelfish can encounter many different problems if you don’t take care of them right. There are many angelfish diseases and illnesses that you should be aware of.

Below, you’ll get information about various diseases and illnesses that impact angelfish. You’ll feel much more prepared to deal with such things when you have an idea of what to expect.

1 – Ich

Snakeskin Barb With Ich or White Spot Disease

Ich is a common condition that angelfish have to deal with. This condition is also colloquially known as white spot disease.

You’ll see tiny white spots on the angelfish when it has ich. This is going to be uncomfortable for the angelfish, and it can also make it hard for the fish to breathe.

There are many symptoms that you can look out for besides just the appearance of white spots. You might notice that your fish will have folded fins if it has ich.

Sometimes angelfish will try to rub against objects in an attempt to remove the white spots. You could see the angelfish struggle to breathe if any of the white spots are located on its gills.

Fish that are experiencing ich will often become disoriented. This can lead to clumsy, unusual swimming behaviors.

It’s very likely that the angelfish will lose its appetite, too. The fish might not eat nearly as much as normal, and in some cases, the fish might stop eating entirely.

How does this happen? Usually, ich is caused by sudden water temperature changes or stress. It’s a type of parasitic infection that only fish with weakened immune systems will have problems with.

Aquatic plants or new fish that you’ve added to the tank might be carrying the protozoa. This can be very bad for your fish, and that’s why you should be careful about what you add to the aquarium in the future.

Thankfully, ich is something that can be treated. You’ll want to quarantine sick fish in a hospital tank and treat them with anti-parasitic medication.

When using this medication, you should remove the carbon filter from the tank. This filter might remove the medication that you’re trying to use to treat the fish.

It can also be helpful to raise the temperature of the water to 86 degrees Fahrenheit. The angelfish can tolerate this but the parasites cannot.

Some angelfish enthusiasts will choose to add salt to the water as well. If you do this, then you must be sure to use aquarium salt and you should only use as much as recommended.

2 – Dropsy

Female Betta With Dropsy Disease

Dropsy is another condition that angelfish enthusiasts need to be aware of. This happens because of an infection, and it usually only occurs when the fish has a compromised immune system.

When a fish has dropsy, it’ll show various symptoms such as looking bloated and having protruding eyes. You might see that the angelfish will have scales sticking out, too.

A fish that is suffering from this condition will often breathe rapidly. It’ll be very lethargic and it probably won’t have much of an appetite.

Sadly, this is something that could easily kill the angelfish. If you don’t notice the condition early, then the chances of saving the fish aren’t great.

Catching the disease early enough will allow you to treat things using antibacterial medications. You’ll want to quarantine impacted fish to try to get them healthy again.

Many also treat fish that have dropsy by using Epsom salts. You generally want to use one-eighth of a teaspoon of Epsom salt for every five gallons of water in the quarantine tank.

3 – Hexamita

Purple Tang With Head and Lateral Line Erosion or Hole in Head Disease

Hexamita might be more commonly known as hole-in-the-head disease. This is caused by the rapid multiplication of parasites in your fish tank.

This is a condition that you need to take seriously. If you don’t treat the fish properly, then it’ll wind up killing them.

There are many different symptoms of hexamita that you should look out for. The first thing that you might notice will involve changes to the stool.

Your angelfish might start producing long, stringy, white stools. This is a big sign that the fish are dealing with hexamita.

Fish that have hexamita will often lose appetite. Eventually, you’ll notice that lesions will develop on the heads of the angelfish.

Of course, you’ll also see the angelfish start to lose color. There are many actions that you can take to try to turn things around and save the fish.

First, you should quarantine the angelfish in a hospital tank. Raise the temperature of the water gradually until it hits 90 degrees Fahrenheit.

Yes, this is hotter than you usually want the water to be when caring for angelfish. However, it’s necessary to try to treat this condition.

Now you’ll want to try to treat the aquarium using medication to treat bacterial diseases. If you continue to care for the fish, then you should be able to nurse them back to health over time.

4 – Swim Bladder Disease

Goldfish With Swim Bladder Issues Swimming Upside Down in Tank

Swim bladder disease is something that many different fish can get. Essentially, this involves the fish having some type of issue with an internal organ known as the swim bladder.

The swim bladder is what helps fish to control their buoyancy, and they aren’t able to swim well when it isn’t working. For example, you might see your angelfish swimming upside down if it’s experiencing the symptoms of swim bladder disease.

Often, this will be a temporary issue that is caused by bloating. You might have fed your fish too much food, and this caused the fish to become constipated.

A constipated fish will have a swollen belly that will press against the swim bladder. This causes the swim bladder to malfunction, and the fish is unable to control its swimming properly.

Sometimes fish will swim upside down, but they might also swim sideways. Depending on the severity of the issue, the fish might not be able to get around very well while experiencing swim bladder problems.

In some cases, fish will have a hard time eating. Other fish might be able to get around fine and live normally even if they have permanent swim bladder damage.

You can solve the swim bladder issue if the cause is constipation. Feeding the angelfish a frozen pea will make it poop a lot, and this will make the swollen belly disappear.

The belly will no longer press against the swim bladder, and all will be well. Of course, other things can cause swim bladder issues.

It’s possible that an infection can cause swim bladder problems. You might need to clear up issues with infection to get the fish to go back to normal if constipation doesn’t seem to be the cause.

You should also consider whether the fish was injured in some ways. Physical trauma has been known to cause swim bladder deformities, and this may or may not get better depending on the severity of the injury.

If a swim bladder condition doesn’t get better, you might choose to euthanize the fish. This isn’t necessary if the fish can get around fine and doesn’t seem to be in pain.

5 – Fin Rot

Patriot Betta With Fin Rot

Fin rot is a serious bacterial infection issue that happens when the water conditions in your tank are less than satisfactory. The bacteria will attack the fins of the angelfish, and the infection will eventually work its way to the base.

Many bacteria can wind up getting into fish tanks when you don’t keep them clean. If you aren’t changing the water out properly, then this could lead to issues with fin rot.

Signs of fin rot are usually related to how the fins look. Examine the angelfish to see if they have issues with their fins.

When a fish has fin rot, the fins are going to appear to be shredded in some way. When the fin rot is advanced, the angelfish might have difficulties trying to swim around.

If the disease manages to spread to other areas of the body, then you might see milky-white areas. You’re going to want to address the situation soon.

Antibiotic treatments can help the fish to get better. You might want to quarantine the infected fish to treat them in a hospital tank.

It’s also going to be imperative to clean the tank properly to prevent this issue from continuing. You should change between 20% and 50% of the water as well.

6 – Velvet Disease

Emperor Angelfish With Gold Velvet Disease

Velvet disease is another type of infection that you should be aware of. This one is caused by a parasite known as Piscinoodinum.

It’s going to attack the body of the angelfish that it infects. This will form a cyst in the slime coating which will wind up breaking through the skin.

If you see that the angelfish has gold, green, or brown cysts all over its body, then it almost surely has velvet disease. This condition also causes excess slime production.

Fish that are infected will experience rapid breathing. They might start rubbing up against objects in the tank to try to get relief.

Eventually, the fish will start to lose its appetite and it’ll be very lethargic. It will start keeping its fins at its side as well.

Treat this condition right away because it can easily kill your fish. Quarantine infected fish in a hospital tank and black out the tank (using a blanket) so that no light can be seen.

Raise the temperature to between 82 degrees Fahrenheit and 86 degrees Fahrenheit. Add aquarium salt to the tank to try to help the fish get better.

Various medications might also help the fish. Popular treatment options include copper and formalin.

Hopefully, the fish will respond to the treatment and get better. If you catch things too late, then the fish will likely perish.

7 – Gill Flukes

Gyrodactylus spp. Under Microscope, Gill Flukes

Gill flukes can be very troublesome for angelfish. This is a parasitic infection that will impact the gills and the skin.

Typically, gill flukes will be caused by stress and problems with improper water parameters. Poor tank conditions will make it much more likely that your angelfish will develop problems with gill flukes.

Parasites wind up burrowing into the skin and they wind up creating ulcers. This can cause secondary infection issues, too.

You can tell whether a fish has gill flukes by looking out for the symptoms. A fish with gill flukes will have gills that look as if they have been chewed or shredded in some way.

You’ll also notice that the fish will start producing far more mucus than normal. General breathing difficulties will follow.

The fish will likely rub its body against objects due to the discomfort that it is experiencing. It might have red skin, too.

You can treat this problem by giving the fish anti-worm medication. Things should get better, but you should also address any issues with your fish tank that might have caused the infection in the first place.

8 – Anchor Worms

Anchor Worms With Egg Sacks on a Fish

Anchor worms aren’t actually worms. They’re crustaceans that wind up embedding themselves into the scales of the angelfish.

Poor naming conventions aside, this is a condition that you should take seriously. Symptoms include general redness, ulcers, and significant inflammation near the spot where the crustaceans have embedded into the scales of the fish.

Fish will have a tough time breathing when dealing with anchor worms. You can try to kill them by giving your fish a potassium permanganate bath that can kill immature anchor worms.

Tweezers can be used to pull embedded anchor worms out, too. It’s recommended to treat the entire aquarium with a special treatment to get rid of the anchor worms, too.

Some might also choose to treat the aquarium with aquarium salt. It can help the fish to get better in this situation, but you can’t use too much of it.

9 – Mouth Fungus Disease

Cotton Mouth Fungus on Black and Yellow Angelfish

Mouth fungus disease is caused by gram-negative bacteria. This is always present in aquariums, but it can cause problems for fish that have weakened immune systems.

This means that stressed fish will be prone to mouth fungus disease. The gram-negative bacteria can enter the fish’s body through wounds.

When the fish experiences this disease, it’ll showcase symptoms such as having cotton-like threads on its mouth, gills, or face. It might also have lesions if the problem is advanced.

The fish will likely experience rapid breathing and it may have ragged fins. Excess mucus production will be noted on the head and the gills.

Treating this condition is as easy as giving the fish antibiotic or antibacterial medications. You might also choose to add aquarium salt to the tank for a time.

10 – Popeye Disease

Fish in Aquarium With Bulging Eyes

Popeye disease is a type of infection that causes fluid to build up behind the eyes of your angelfish. This is generally triggered by poor water conditions.

The fish does have a risk of dying when it experiences popeye. The eye could also become damaged or even fall out if things get really bad.

Symptoms of this disease include cloudy eyes that appear to be protruding from the head. You also might see that the fish has ruptured eyes, and the fish could experience vision loss.

To treat this condition, you’ll want to do a 50% water change each day for four days straight. This is to try to get the water conditions back where they should be.

It’s also a good idea to consider adding Epsom salts to the tank. Using one teaspoon for every gallon of water should be fine.

Antibiotics can be mixed into the fish food as well. Your fish should be able to get better if things aren’t too advanced.

11 – Cotton Wool Disease

Long Finned Surpae Tetra With Cotton Wool Disease

Cotton wool disease often occurs due to having an overcrowded fish tank. You should never try to stuff too many fish in a tank that is too small.

Poor water conditions and water temperatures that dip too low can contribute to these issues as well. Symptoms of the disease include fish developing a translucent layer on the skin.

You might notice that the edges of the fish will start to look bloody, too. It might appear as if the blood is oozing through the skin.

If the disease is advanced, then you will need to euthanize the fish. Catching the disease early might allow you to try to turn things around.

You’ll want to fix the environmental issues that caused the disease. Do water changes, clean the tanks, and solve the overcrowding issue in your fish tank.

Add marine salt to the tank and treat the water using potassium permanganate. It should help the fish to get healthy again.

12 – Viral Infection

Koi Angelfish Near Bottom of Tank With Tucked Fins

Angelfish can also get a viral infection that is sometimes referred to as angelfish AIDS. This is a terrible viral infection that can easily kill your angelfish.

Typically, angelfish wind up dying within a few days of contracting the virus. It’s also horrible that this virus can easily spread from one fish to another.

When a fish has this viral infection, it’ll become incredibly weak. The angelfish might have fins that are folded against its body.

You’ll notice that the fish will start producing more slime than usual. It’s very likely that the fish will hang out at the bottom of the tank, too.

Often, angelfish will point their noses up when suffering from this viral infection. It’s unlikely that you will be able to save the fish if it is infected.

You can try to quarantine the fish to avoid infecting other fish in the tank. Treat the fish tank with special medicine and hope that it helps.

Every time you give the fish the treatment, it’s recommended to change 10% of the water. You might not save the fish because this condition is so bad.

If the fish does appear to get better, then you should wait to transfer it back to the main tank. It’s possible for a fish to carry this virus for up to six months.

Final Thoughts

Platinum Angelfish in a Freshwater Aquarium

Many of these conditions are caused by improper conditions in the fish tank. For this reason, it’s going to be imperative to keep a close eye on water parameters.

Always ensure that you keep the fish tank in the right temperature range. Remember that angelfish like the temperature of the water to stay between 76 degrees Fahrenheit and 84 degrees Fahrenheit under normal conditions.

You want to keep a close eye on the pH balance of the tank as well. Things should stay between 6.8 and 7.8, and you’ll want to use chemicals to adjust things if something gets thrown off.

Keeping the tank clean is very important, and this means that doing water changes will be necessary. You should endeavor to change out 15% of the water each week.

Try to get into the habit of doing this and it won’t be a big deal. Also, it’s good to try to reduce stress factors so that your angelfish won’t develop compromised immune systems.

Never overcrowd the fish tank because it makes everything worse. This stresses the fish and makes it more likely that the tank will get dirty quickly.

Try to get a big tank for your fish so that they will have more than enough room to swim. Otherwise, it’d be better to severely limit the number of fish that you put in a tank.

Keep all of this in mind and you should be able to keep many diseases at bay. It’ll still be wise to keep an eye on your fish, though.

Being an observant, proactive fish owner can help you to notice issues before they become too bad. Hopefully, you’ll be able to save the fish if something ever goes awry.

You love your angelfish, and you can do your best to keep enjoying them for a long time. Just putting in the effort will make a huge difference.

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Paul Choate

Wednesday 7th of December 2022

One of my Angel fish seems to have a protruding annus. This is something new. I have had this fish going on 7 yrs. It is eating well and has no other noticeable changes. Is this something to be concerned about?