The Ultimate Angelfish Diseases Guide

For thousands of years, angelfish have been kept in captivity by enthusiast aquarists who aim to enhance the beauty of their aquarium.

However, while angelfish are known to be hardy and quite easy to keep even for beginners, they can easily fall prey to various diseases.

And if you are caring for angelfish, chances are that at some point you’ve experienced the stress and mortality associated with illness.

Therefore, it’s important to familiarize yourself with these common angel fish diseases so that you can recognize them and deal with them immediately.

Thankfully, we’re here to help! We will go through all you need to know about angelfish diseases, their causes, symptoms, treatment, and prevention.

So, without further ado, let’s jump right into it!

Angel Fish Diseases

There are several well-known diseases that affect the ornamental tropical fish community, including Black Disease (Brooklynella hostilis), Velvet (Oodinium sp.), Head and Lateral Line Erosion (HLLE, aka Hole-in-the-Head Disease), Flexibacter infections like Flexibacter Columnaris (Flex for short) or Saddleback disease, and Marine Ich.

The chances that your fish might catch any of these diseases vary, however, if you do notice any of these or other infections in your tank, then you need to act immediately.

Here is a list of all the most common freshwater angelfish diseases, causes, symptoms, and how to treat them.

1. Fin and Tail Rot

a. Causes

Fin and tail rot is a kind of fish disease that can occur to any fish not only angelfish.

Normally, these infections are caused by a group of bacteria known as Aeromonas.

The bacteria can invade the fish’s body through injuries, such as those sustained after an angelfish is attacked by another fish. 

Fin rot can also occur if water quality is poor or if the angelfish is exposed to sudden temperature changes, both these situations lower the natural immunity of the fish, which increases the chances of fungal infection.

b. Symptoms

  • This disease causes visible changes that include holes in the fins or discoloration of them. 
  • It also causes dark spots to appear on the body, something which is especially visible on angelfish of lighter color. 

c. Treatment

Fin rot can be treated with antibiotics if the infection is relatively mild.

More serious cases will require stronger solutions that are administered through intramuscular injections or even intravenously.

d. Prevention

Fin and tail rot is a highly contagious disease, so it spreads from fish to fish very quickly.

The best way to prevent Fin and tail rot is by:

  •  maintaining good water parameters in the tank. 
  • avoiding chemical exposure (such as formalin).
  • making sure that the angelfish are in ideal living conditions.

2. Columnaris

Columnaris (also called mouth and fin rot) is a bacterial infection that can be fatal to aquarium fish. 

Although it has been around since the 1940s, when antibiotics were not readily available to hobbyists, and still continues to cause huge losses in our hobby today.

a. Symptoms

Columnaris is a common bacterial infection, It can spread to other fish very easily if they are housed in the same tank with the rising of symptoms such as:

  • small white spots on the fins, which will gradually develop into large patches of white (hence its name).
  •  The body may also display symptoms like redness and inflammation.

b. Causes

Columnaris is more likely to occur due to:

  • Poor water quality.
  • The aquarium has insufficient aeration, and the fish are of a weak species. 
  • Columnaris’ bacteria thrive in warm water and stressful conditions such as those brought on by sudden changes in temperature or pH. 
  •  Overstocking.
  • The addition of new fish that’s a carrier of the disease to an established healthy tank.
  • It can occur as a secondary infection resulting from other illnesses, such as fin rot and Velvet (gold dust disease) or aggressive behaviors.

c. Treatment

When you first start noticing symptoms of Columnaris, move the infected fish to a separate aquarium so that it doesn’t infect any other fish.

Then, treat the tank with an antibiotic solution so you can kill off the bacteria causing the disease.

There are numerous antibiotics that can be used to treat this disease, including: 

  • Furan-2 
  • Furan-3

It is very important for the tank to have a culture of live bacteria before treatment can begin because this will provide a good environment for the medication to work in.

d. Prevention

Columnaris outbreaks are typically controlled by the following steps:

  1. Making regular water changes and maintaining the aquarium’s Tank, includes vacuuming the gravel.
  2. Changing 20-30% of your filter media every week (or more if it becomes dirty).
  3. Keep an adequate amount of food in with your fish so that they don’t starve to death.
  4. Removing any dead or dying plants from around them as well because these will also cause problems for them too.

3. Pop Eye

a. Causes

Pop-eye is a common sign of underlying disease, it can be caused by many things including bacterial infections or physical damage to the fish’s eyes. 

It occurs as a result of fluid retention behind the eye or along the spine which causes the eye(s) to protrude. 

Other causes may include physical damage, poor nutrition, or tumors on the fish.

b. Symptoms

  • Popeye disease is a condition that causes the eye of a fish to swell and protrude from the head, giving it a pronounced appearance.
  •  If a fish has popeye, it will often continue to worsen until the eye is completely out of its socket.
  • Popeye will usually strike both eyes if one goes blind because of damage, This is because the other eye will compensate for the damaged one until it too becomes affected by popeye.

c. Treatment

If your fish have a popeye you should follow these steps:

  • You should first move them to a separate tank and treat them with Kanamycin sulfate or Nitrofurazone as per an appropriate medication schedule. 
  • Treating with antibiotics while the fish is in a QT tank allows you to track the progress of the disease and will also help prevent other infections from developing. 
  • A bacterial infection may develop if your fish do not respond to Kanamycin sulfate or Nitrofurazone so it is recommended to add 1 tbsp of aquarium salt per 5 gallons if following a Kanamycin sulfate or Nitrofurazone treatment didn’t bring up much results.

After your fish have been properly treated, you should move them back into the main tank and monitor for any signs of popeye reappearing.

If popeye appears again, repeat treatment and add 1 tbsp of aquarium salt per 5 gallons.

d. Prevention

  • Keep the tank water temperature at about 78 degrees Fahrenheit, and keep the tank’s pH within the range of 6.8 – 7.5 .
  • Use a filter for biological filtration, such as an under gravel filter or sponge filter, This helps to remove ammonia before it can harm your fish by causing Pop Eye disease or other infections.
  • Feed your fish a high-quality food, flake food diet that has been formulated to provide all the nutrients they need without overfeeding them or polluting the water.
  • Keep the tank clean and free of decaying plant matter by changing about 20 percent of its water each week, vacuuming the gravel with a siphon or gravel vacuum.
  • Avoid overfeeding your fish because this can cause the water to become polluted with ammonia, create poor water conditions which further stress your angelfish and make it more susceptible to Pop Eye disease or other infections.
  • Get rid of any decaying plant matter or dead animals in the tank immediately.

4. Cloudy eyes

a. Causes

some of the causes of cloudy eyes in fish:

  •  Bacterial infection.
  •  parasitic infection.
  •  water quality issues.
  •  injury to the eye as well as physical stress caused by illness and fish transport.

b. Symptoms

  • Cloudy or opaque eyes.
  • loss of color in the fins and/or skin. 
  • Fish may rub against objects and become lethargic and perhaps die.

c. Treatment

  • Treat with a good anti-fungal medication such as API Fungus Cure.
  • Comfort Zone, Melafix, and Pimafix are natural remedies that may help but take care not to confuse these with the above-mentioned medications.
  •  Infected angelfish need a quarantine tank for treatment. 

5. Furunculosis

The disease known as furunculosis is a highly contagious illness that affects fish of all ages.

a. Causes

Aeromo-nas salmonicida is a Gram-negative bacterium that causes furunculosis, which is probably the most frequent bacterial infection in cultured salmonids.

b. Symptoms

  • The fins on the fish become frayed.
  • Appetite loss.
  • Lethargy.
  • The fish’s color fades and turns pale.

c. Treatment

The illness is treated on farms with medicine or vaccination.

6. Ich (White spot Disease Or Ick)

a. Causes

Ich is the most common disease among aquarium fish.

It’s caused by Ichthyophthirius multifiliis, a ciliated protozoan parasite of freshwater fish (also known as white spot disease or ick).

b. Treatment

  1. Perform a partial water change every couple of days and keep the aquarium lights off for as much of the day as possible (this will help prevent outbreaks if you don’t have medication on hand).
  2. Use an Ich medication such as Acriflavine (sold under various trade names). If you can’t get your hands on this, try one of the alternative treatments mentioned earlier.

If you follow this regime for 5-7 days (longer if there are recurrences of ich), it should fully heal or at least subside to a point where the fish won’t show any more symptoms.

Be aware that Ich can be fatal to some fish, particularly if they’re already under stress or have low immunity. 

If you notice that the symptoms worsen or the fish stops eating, take action immediately!

c. Symptoms

  • Swimming Erratically.
  • Lethargy and Emaciation.
  • On the gills and remainder of the body, tiny white spots & patches appear.
  • Appetite loss.

d. Prevention

  • Perform Weekly Water Changes.
  • Maintain Good Water Quality.
  • Declutter Your Tank.
  • Don’t Overstock Your Tank.

6. Marine Velvet 

a. Causes

Marine velvet is caused by an infestation of a parasitic protozoan called Amyloodinium ocellatum.

b. Treatment

Marine velvet can be treated with salt dips, copper sulphate baths, and by adding a parasiticidal agent such as formalin to the aquarium water.

c. Symptoms

  • Scratching, flashing, and rubbing against objects in the tank.
  • Lethargy and loss of appetite.
  • Sunken eyes and pale coloration.
  • There may be rapid breathing or labored respiration due to fluid buildup around the gills. 
  • There may be fin erosion and/or scale damage
  • Rapid gill movement, gasping at the surface, and a distended abdomen.

d. Prevention

There are two factors for preventing marine velvet: 

  • Maintaining good water quality. 
  • Quarantine. 

When introducing new fish into an aquarium it is very important to quarantine them for at least two weeks before putting them in with the other angelfish, During this time they should be treated for parasites.

Otherwise, when your tank is infected and all the angelfish have been infected, you will have to treat them all at the same time.

7. Hole in the Head

a. Causes

Hole in the Head disease is caused by three factors: environmental, bacterial, and parasitic infection.

  1. Environmental causes of Hole in the Head Disease such as:
  2.  increased nitrates or phosphates in your aquarium water.
  3. increasing the pH level above 8.2.
  4. low CO2 levels. 
  5. lack of algae for herbivorous fish to eat.
  6. overcrowding, and other factors.
  7. Pathogenic bacteria cause Hole in the Head Disease such as:
  8. proliferating rapidly in an environment where fish are stressed or poorly fed. 
  9. Fish that eat a lot of protein and fat have low immunity to disease.
  10. Parasitic causes of Hole in the Head Disease include:
  11. Costia.
  12. Chilodonell.
  13. Trichodina.
  14. Trichophrya.

These parasites thrive in an environment where fish do not eat properly or are under stress from other sources.

b. Treatment

Since the hole in the head fish disease may be due to a variety of reasons, most often it is treated with a multi-pronged approach:

  • Your fish will require vitamin and mineral supplementation, as well as good nutrition.
  • regular water changes and nitrate reduction.
  • Removing activated carbon.
  • Providing them with a sufficient amount of vitamins and iodine.

c. Symptoms

  • They typically have pitting and erosions along the head and/or lateral line.
  • Loss of appetite
  • Lethargy
  • Swollen body

d. Prevention

Hole In The Head Disease is a serious condition that can be fatal. 

By following these simple steps, you can help keep your fish safe and healthy.

  • Keep your water quality high by doing regular water changes and using a good quality filter.
  • Feed your fish a healthy diet with plenty of variety.
  • Provide them with plenty of places to hide and swim.
  • Keep your tank clean and free of algae.
  • If you notice any symptoms of Hole In The Head Disease, treat your fish immediately.

8. Lymphocystis

Lymphocystis is a fish disease that can affect both skin and fins. This infection occurs when an iridovirus called LCDV assaults your fin tissue, leading to lumps or splotches on their body

a. Causes

The virus may be caught by direct contact with infected fish or through their aqueous environment. 

Once lymphocystis enters a water system from an infected fish, it can survive for up to 1 week in the surrounding water.

Many fish may be latent carriers of the virus that don’t show symptoms.

The virus may not show up until weeks or up to six months of quarantine, Quarantine protocols may be done by the time the virus appears.

b. Treatment

There is no cure for lymphocystis. Clinical symptoms of lymphocystis are exacerbated by other tank stresses, such as poor water quality, poor nutrition, or inappropriate temperatures. 

Your fish may recover their previous appearance by alleviating some of these problems.

Because it has no effect on the fish’s health or wellbeing, it is of little concern to most fish owners.

c. Symptoms

The symptoms of lymphocystis include:

  •  The development of large, cauliflower-like lumps on the skin and fins. 
  • In severe cases, the movement of the fish might be affected due to the large growth of the lumps.

d. Prevention

It is very hard to catch lymphocystis outbreaks even if you are practicing proper quarantine. 

Lymphocystis is a disease that has a long incubation period, It can be in your tank and you would not know it.

9. Nematodes (Roundworms)

Nematodes are a deadly fish affliction that is difficult to cure once it has occurred.

a. Causes

  • eating organic food.
  • Remainders of uneaten food.

b. Treatment

  • Parachlorometaxylenol is used to treat fish.
  • Decreasing the amount of fish food would help.
  • You can add Gourami or Pleco fish to your tank.

c. Symptoms

  • Worms come out of the anus when a fish suffers from this illness.
  • Lethargy.
  • Loss of appetite.
  • Sink belly.

d. Prevention

Preventive medicine entails ongoing checking of susceptible juveniles or broodstock (by regular fecal exams and necropsies of small numbers of fish) as well as decreasing the presence of intermediate hosts, including fish-eating birds and tubifex worms, as mentioned above.

10. Argulus ( Fish Lice Or Fish Louse )

Fish lice (Family: Argulidae), more commonly known as fish louse, are branchiuran parasites at infest and cause disease in fish.

a. Causes

Argulus infections are caused by the fish louse, a small parasitic crustacean that lives on the skin and gills of fish

b. Treatment

  • Remove the parasites by using tweezers.
  • Clean the wound with an antiseptic solution. 
  • While manually removing them, use a specialized medication.

c. Symptoms

The symptoms of an argulus infection depend on the severity of the infestation. 

  • In mild cases
  •  The fish may have a few small lesions on their skin. 
  • In more severe cases
  •  The fish may have large areas of skin that are inflamed and covered in parasites. 
  • In the most extreme cases
  •  the fish may die from the infection.

d. Prevention

  • Incoming fish, especially wild-caught or pond-raised stock, should be quarantined, observed, and examined to reduce the chance of introduction.
  • If there is an outbreak of Argulus, it should be managed quickly. 
  • Source water should be checked for possible argolid egg introduction as a way of preventing future infestations.
  • Filters or water from a fish-free and Argulus-free source should be used. 

How Can I Prevent My Angelfish From Getting Sick?

While it’s a good thing to know about these diseases, you need to make sure that they don’t actually make their way into your fish tanks.

The most important thing to do when you’re caring for your angel fish is to create a healthy environment so your fish don’t get sick. 

You shouldn’t introduce new fish to your tank, or trade with other hobbyists if you do not quarantine the new arrivals for at least two weeks (the quarantine period required by most breeders and sellers).

You want to make sure whether the new arrivals have any disease and what type of disease they might be carrying before it infects your existing population or you might get secondary infections or angelfish virus.

Do I Need to Quarantine My Existing Fish If I Introduce a New Member?

It is a common practice to quarantine any new arrivals that you bought from a local fish store for at least two weeks, but sometimes it can be even longer.

If you have an ill angelfish then the quarantine period will help keep those symptoms from being transmitted to other fish species.

Similarly, if your angelfish carry diseases that they can pass on to other fish then the quarantine will prevent those symptoms from infecting your tank and compromising fish health.

It is also a good idea for you to observe any new fish carefully and learn their behaviors so you recognize any symptoms of disease before it spreads across your tank – even though most angelfish diseases are easily preventable.

How Do I Know If My Angelfish Is Sick?

The most obvious signs of disease include discoloration, lethargy or loss of appetite, gasping for air, swimming in abnormal patterns or positions, and sitting on the bottom of the tank.

There are other symptoms to watch out for: red streaks can appear on the freshwater angelfish, fat deposits around the eyes will disappear, and the skin may start to corrode. 

When you see any of these symptoms in your angelfish then it’s time to act fast.

What Should I Do If I Notice That My Angelfish Are Sick?

If you see signs of disease in your fish then you have to act fast. 

One of the best ways to treat angelfish is through aquarium salt, which helps remove toxins from the water and reduces stress levels among your fish.

Other treatment methods include using Kanamycin or Gentamicin. 

if Flexibacter is the problem, along with Colistin for Columnaris. You can also use Metronidazole or Tetracycline for ulcer disease.

What Is The Best Way to Cure My Sick Fish?

The most crucial thing is to replace the water in your tank so you have a fresh batch of saltwater available, with no traces of ammonia or nitrites.

Test your aquarium to see if your levels of ammonia and nitrite are zero before you add water to the tank.

Then add a tablespoon of salt per gallon of water in your tank, or follow the directions on your aquarium salt packaging. 

If you have a quarantine tank then you want to transfer the sick angelfish from your main tank to some sort of an isolation tank so they can fully recover.

How Can I Prevent a Disease From Spreading?

There are a few things you can do to minimize the spread of a disease in your aquarium. 

For example, make sure that you keep the water in your tank clean at all times by doing frequent partial water changes with fresh saltwater. 

Avoid any overcrowding issues and provide plenty of hiding spaces in your tank. Make sure you aren’t overfeeding any of your fish, and be careful when putting your hands into the aquarium so that bacteria from your body don’t spread to the water.

How Can I Keep My Angelfish Disease-Free?

There are several ways to prevent diseases from infecting your freshwater angelfish. 

The first is to buy angelfish from a breeder or seller who guarantees their fish and provides them with a clean and healthy environment, and the second is to quarantine any new saltwater angelfish for at least two weeks before introducing them into your tank (which means that you can be sure that they aren’t carrying disease).

You should also watch out for any symptoms of illness, and treat your fish as soon as you see anything wrong.

Last Words

As long as you’re aware of these common angelfish diseases then it’s possible to keep your fish healthy and free from disease.

With time, experience, and proper care, there’s no reason why your saltwater angelfish shouldn’t enjoy a long and happy life.

We hope you have enjoyed this article as much as we did.

If you still have any questions please share them with us in the comment section below.