15 Angelfish Diseases & Their Treatments: A Complete Guide

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Having Angelfish in my tank has been a real learning experience. These fish aren’t just a treat for the eyes; they’re also pretty straightforward to care for.

Still, like any living thing, they can run into health issues, and that’s when I step in.

Dealing with fish health problems is a bit of an art, and it’s particularly true for Angelfish with their unique traits.

That’s why I decided to put together this guide.

Here, I’ve covered 15 common health issues Angelfish might encounter and provided some well-researched fixes for each.

Let’s get into it.

Also Read: Angelfish Care Guide

1. Ich (Ichthyophthirius multifiliis)

Ich, also known as “white spot disease,” is a common and highly contagious parasitic infection in Angelfish.

It’s caused by a protozoan parasite that attaches itself to the fish’s skin, gills, and fins. Early detection and treatment are crucial to prevent its spread to other fish in the tank.


  • White, salt-like spots on skin, fins, and gills.
  • Fish rubbing or scratching against objects.
  • Clamped fins and lethargic behavior.
  • Rapid gill movement or labored breathing.
  • Loss of appetite and weight loss.


  • Gradually increase water temperature to 80-82°F over 48 hours to speed up the parasite’s life cycle.
  • Use a commercial ich treatment like Coppersafe (link to Amazon) following package instructions, typically involves dosing for several days.
  • Perform partial water changes (25-30%) daily to remove parasites from the water.
  • Add aquarium salt (1-2 teaspoons per gallon) as a supportive treatment, unless contraindicated by other tank inhabitants.

Also Read: Angelfish Ich

2. Fungus

Fungus in Angelfish manifests as cotton-like growths on the fish’s body, often a result of poor water quality or injury.

It’s a secondary infection that exploits compromised fish, making quick action essential to save the affected fish.


  • Cotton-like, fluffy growths on skin, mouth, or fins.
  • Discoloration or erosion around the affected area.
  • Reduced activity and swimming ability.
  • Loss of appetite and weight.
  • Rapid gill movement or labored breathing.


  • Improve water quality by performing a 30-50% water change and regular maintenance.
  • Isolate affected fish in a hospital tank if possible to prevent spread.
  • Treat with a commercial antifungal medication, following the manufacturer’s instructions. My recommendation: Seachem PolyGuard (link to Amazon).
  • Add aquarium salt (1 teaspoon per gallon) to support healing, unless contraindicated.

Also Read: Angelfish White Fungus Disease

3. Fin Rot

Fin rot is a bacterial infection that affects the fins and tails of Angelfish, often due to poor water conditions or injuries.

It starts at the edges of the fins and can progressively worsen, leading to extensive tissue damage.


  • Fins or tail appear frayed or ragged.
  • Red, inflamed edges on fins.
  • Fins shrinking or shortening.
  • Slime or mucus on affected areas.
  • Behavioral changes like lethargy or loss of appetite.


  • Improve tank conditions with regular 25-30% water changes and filtration.
  • Quarantine affected fish to prevent the spread of infection.
  • Administer a broad-spectrum antibiotic or antibacterial medication as per guidelines. I personally found success with the API FIN & BODY CURE (link to Amazon).
  • Maintain a stable water temperature and monitor water parameters for nitrate, nitrite, and ammonia levels.

Also Read: Angelfish Fin Rot

4. Hole in the Head

Hole in the Head disease in Angelfish is a mysterious ailment characterized by pitting and sores on the fish’s head and body.

It’s thought to be linked to nutritional deficiencies and poor water quality, making a holistic approach essential for treatment.


  • Small pits or holes on the head and lateral line of the fish.
  • Discoloration or ulceration around the affected areas.
  • Loss of appetite and weight.
  • Lethargy and disinterest in normal activities.
  • Increased mucus production.


  • Enhance water quality with regular changes (25-30%) and efficient filtration.
  • Improve diet with high-quality, varied foods rich in vitamins and minerals. My recommendation: Seachem Nourish (link to Amazon).
  • Treat with a commercial medication specifically designed for Hole in the Head disease.
  • Add vitamins and supplements to the water or food as recommended by an aquatic veterinarian.

Also Read: Angelfish Hole In The Head

5. Popeye Disease

Popeye disease in Angelfish is characterized by the swelling of one or both eyes, often caused by bacterial infections, injuries, or poor water quality.

It’s important to treat both the symptoms and underlying causes to ensure a full recovery.


  • One or both eyes bulging abnormally.
  • Cloudiness or haze over the affected eye.
  • Inactivity or hiding more than usual.
  • Refusal to eat or decreased appetite.
  • Color fading or loss of luster.


  • Conduct a 30-50% water change and maintain pristine water conditions.
  • Quarantine the affected fish to prevent the spread of infection.
  • Administer an appropriate antibiotic or anti-inflammatory medication as prescribed.
  • Ensure a balanced diet with vitamins and supplements to boost the fish’s immune system.

Also Read: Angelfish Popeye Disease

6. Black Spot Disease

Black Spot Disease, also known as Diplopstomiasis, is caused by a type of parasitic flatworm.

It’s often seen in wild fish but can appear in aquariums through snails or plants.

The disease manifests as tiny black spots on the skin, fins, and gills of Angelfish, typically not fatal but can cause discomfort.


  • Small black or dark spots on the skin, fins, and gills.
  • Scratching against objects due to irritation.
  • Clamped fins or abnormal swimming patterns.
  • Reduced feeding or loss of appetite.
  • Mild lethargy or decreased activity levels.


  • Treat the entire aquarium with an anti-parasitic medication as per the product’s instructions. My recommendation: Fritz Mardel Coppersafe (link to Amazon).
  • Perform regular water changes (25-30%) to reduce parasite load.
  • Remove snails or other potential intermediate hosts from the aquarium.
  • Ensure good water quality and reduce stressors to boost the fish’s immune system.

Also Read: Black Spots On Angelfish

7. Dropsy

Dropsy in Angelfish is a symptom rather than a specific disease, often indicative of kidney failure or bacterial infection.

It’s recognized by the swelling of the fish’s body and the protrusion of scales, resembling a pinecone. It’s serious and often fatal if not treated promptly.


  • Swollen or bloated abdomen.
  • Scales sticking outwards, resembling a pinecone.
  • Eyes may bulge out (exophthalmia).
  • Pale gills and lethargy.
  • Loss of appetite and swimming difficulties.


  • Isolate the affected fish in a hospital tank to prevent spread.
  • Treat with a broad-spectrum antibiotic after consulting a veterinarian.
  • Increase water temperature slightly to promote metabolism and healing.
  • Offer high-quality, easily digestible food to support recovery.

Also Read: Dropsy In Angelfish

8. Constipation

Constipation in Angelfish is usually a dietary issue, often caused by overfeeding or a lack of dietary fiber.

Symptoms include bloating and a reduced ability to defecate. Prevention is key, focusing on a balanced diet and proper feeding practices.


  • Swollen or distended abdomen.
  • Infrequent or no bowel movements.
  • Loss of appetite or refusal to eat.
  • Lethargic behavior and less swimming activity.
  • Stringy or long feces hanging from the fish.


  • Temporarily fast the fish for 24-48 hours to alleviate digestive strain.
  • Feed a pea (cooked, skinned, and mashed) to help clear the digestive tract.
  • After fasting, reintroduce a high-fiber diet with foods like blanched spinach.
  • Ensure regular feeding schedules and avoid overfeeding.

Also Read: Angelfish Constipation

9. Swim Bladder Disorder

Swim Bladder Disorder in Angelfish affects their buoyancy, often due to overfeeding, constipation, or infection.

Fish might float uncontrollably or struggle to maintain their position in the water, impacting their quality of life.


  • Difficulty swimming, either sinking or floating involuntarily.
  • Floating upside down or at a strange angle.
  • Bloated abdomen indicating possible constipation.
  • Lack of coordination in swimming movements.
  • Reduced appetite and inactivity.


  • Fast the fish for 24-48 hours to relieve pressure on the swim bladder.
  • Feed a cooked, skinned pea to aid digestion and alleviate constipation.
  • Ensure water quality is optimal, adjusting temperature and pH as needed.
  • In cases of suspected bacterial infection, consult a vet for specific treatments.

Also Read: Angelfish Swim Bladder Disorder

10. Gill Flukes

Gill Flukes are parasitic flatworms that infect the gills of Angelfish, causing severe irritation and respiratory distress.

They’re microscopic but their effects are noticeable, requiring prompt treatment to prevent serious health issues.


  • Rapid or labored breathing.
  • Reddened or swollen gills.
  • Excessive mucus production on the gills.
  • Fish rubbing gills against objects in the tank.
  • Reduced activity and loss of appetite.


  • Treat the tank with a praziquantel-based medication, following manufacturer’s guidelines.
  • Increase aeration in the tank to support oxygenation during treatment.
  • Perform regular water changes (25-30%) to improve water quality and reduce parasite load.
  • Quarantine new fish before introducing them to the main tank to prevent reinfestation.

11. Velvet Disease

Velvet Disease, also known as Gold Dust Disease, is a parasitic infection in Angelfish caused by dinoflagellates.

It’s recognized by a fine, yellowish or golden dust-like coating on the fish’s body.

This contagious disease can rapidly deteriorate the fish’s health and is often fatal if not treated promptly.


  • Fine, yellowish or gold dust-like coating on the skin.
  • Scratching or rubbing against objects in the tank.
  • Clamped fins and lethargy.
  • Loss of appetite and rapid weight loss.
  • Breathing difficulties and clouded eyes.


  • Dim the lights in the aquarium, as the parasite thrives in light.
  • Treat the water with copper-based medications, following the manufacturer’s instructions. My recommendation: Seachem Cupramine Copper (link to Amazon).
  • Perform regular water changes (25-30%) to remove free-swimming parasites.
  • Increase temperature slightly to speed up the parasite’s life cycle for effective treatment.

12. Bacterial Infections

Bacterial infections in Angelfish can manifest in various forms, often as a result of poor water quality, injuries, or stress.

Symptoms and severity can vary, but they generally lead to systemic health issues and require immediate attention.


  • Red streaks or sores on the body and fins.
  • Ulcers or open wounds on the skin.
  • Swollen or bloated abdomen.
  • Fading color and lethargy.
  • Loss of appetite and abnormal swimming behavior.


  • Isolate the infected fish to prevent the spread of the disease.
  • Improve water quality with frequent water changes and proper filtration.
  • Treat with a broad-spectrum antibiotic, either in the water or through medicated food.
  • Support the fish’s immune system with a nutritious diet and stable water conditions.

13. Columnaris

Columnaris, caused by Flavobacterium columnare, is a bacterial infection affecting many freshwater fish, including Angelfish.

It can attack various parts of the fish, including skin, gills, and fins, often mistaken for fungal infections due to its appearance.


  • Cottony or fuzzy patches on the skin, fins, or gills.
  • Ulcers or lesions on the body.
  • Rapid gill movement and labored breathing.
  • Eroded fins or tail.
  • Lethargy and loss of appetite.


  • Isolate affected fish to a hospital tank to prevent the spread.
  • Treat with antibiotics such as kanamycin or erythromycin as per guidelines.
  • Improve water quality with regular changes and adequate filtration.
  • Increase water temperature slightly to enhance the effectiveness of some medications.

14. Lymphocystis

Lymphocystis is a viral disease common in freshwater fish, including Angelfish.

It’s characterized by the growth of wart-like lumps on the fish’s body. While not usually fatal, it can affect the fish’s quality of life and appearance.


  • Small, wart-like growths on fins, body, or mouth.
  • Growth of lumps over time.
  • Affected fish may become lethargic.
  • Difficulty swimming due to the growths.
  • Otherwise normal feeding and behavior.


  • There is no direct treatment for viral infections like Lymphocystis.
  • Maintain high water quality to prevent secondary infections.
  • Provide a balanced diet to strengthen the immune system.
  • Growth typically regresses on its own; monitor the fish for any changes.

15. Neon Tetra Disease

Neon Tetra Disease, caused by the parasite Pleistophora hyphessobryconis, affects not only Neon Tetras but also other fish like Angelfish.

It’s highly infectious and often fatal, characterized by progressive wasting and loss of color.


  • Fading color, especially in the neon stripe.
  • Restlessness and irregular swimming.
  • Cysts may form under the skin, causing lumps.
  • Wasting body despite normal feeding.
  • Eventually, difficulty in swimming and loss of equilibrium.


  • There is no known cure for Neon Tetra Disease.
  • Remove affected fish immediately to prevent spread to other tank inhabitants.
  • Maintain excellent water quality to support the health of other fish.
  • Ensure a varied and nutritious diet for the remaining fish to boost their immune systems.

Are Angelfish Prone to Disease?

Yes, Angelfish are prone to diseases, especially when water conditions are not ideal or when they are stressed.

They require careful maintenance of their environment and a balanced diet to stay healthy. Regular monitoring for signs of illness is crucial for early detection and treatment.

Also Read: Stress In Angelfish

Which Disease Is Most Common in Angelfish?

The most common disease in Angelfish is Ich, characterized by white spots and irritability. 

Additionally, Fin Rot and Fungus are also quite prevalent, often resulting from poor water quality or injury.

These conditions underscore the importance of maintaining clean and stable aquarium conditions.

In Which Diseases Is It Best to Isolate My Angelfish?

In diseases like Dropsy and Bacterial Infections, it’s best to isolate your Angelfish to prevent the spread to other tank mates and manage treatment effectively.

Columnaris, being highly contagious, also warrants isolation of the affected fish for targeted care.

Similarly, for conditions like Neon Tetra Disease, isolation is crucial as there is no cure, and it’s highly infectious.

Tips for Maintaining an Ideal Hospital Tank for Angelfish

Maintaining an ideal hospital tank for Angelfish is essential for treating sick fish effectively and minimizing stress.

It should be a stable, controlled environment that mirrors the main tank but allows for close monitoring and treatment.

  • Proper Size: A hospital tank should be around 10-20 gallons, large enough for the Angelfish to move comfortably but small enough for effective treatment.
  • Water Parameters: Match the water temperature and pH to the main tank (typically 76-82°F and pH 6.8-7.8) to avoid additional stress on the fish.
  • Basic Filtration: Equip the tank with a sponge filter or a gentle filter to keep water clean without strong currents that could stress the sick fish.
  • Minimal Decor: Keep decorations minimal, like a small hiding place, to reduce stress while ensuring the fish can be observed easily for any changes in condition.

How Do I Consult an Aquarium Vet?

When consulting an aquarium vet, it’s important to provide detailed information about your sick fish and its environment to get the best advice.

  • Detailed Symptoms: Describe the symptoms in detail, such as changes in behavior, appearance, and eating habits, to help the vet diagnose the problem accurately.
  • Tank Conditions: Inform the vet about your tank’s size, water parameters (temperature, pH, ammonia, nitrite, and nitrate levels), and any recent changes to the environment.
  • Fish Diet: Share details about what you feed your Angelfish, including the type of food, frequency, and amount, as diet can influence health.
  • Treatment History: If you’ve attempted any treatments, inform the vet about what was used, dosages, and how the fish responded to these treatments.

Also Read: Angelfish Eggs Care


Maintaining proper water conditions is essential to avoid many of the diseases we discussed, which is definitely good news.

But, if you notice any signs of illness in your Angelfish, the first step is to isolate the fish to prevent spreading the disease to others, and think about changing the water.

After that, I highly recommend talking to an aquatic veterinarian for further advice and recommendations.