The Fish Keeping & Aquarium Guide.

Why Are My Angel Fish Turning Yellow? Exploring the Possible Causes

Affiliate Disclaimer

As an affiliate, we may earn a commission from qualifying purchases. We get commissions for purchases made through links on this website from Amazon and other third parties.

Angel fish are a popular species among aquarium enthusiasts, and it can be concerning when they start to show signs of discoloration. One common issue is when angel fish turn yellow, which can be a symptom of various underlying problems.

This article will explore the possible causes of yellowing in angel fish and what can be done to prevent or treat it.

Yellowing in angel fish can be caused by various factors, including poor water quality, stress, and disease.

If the water quality is not optimal, it can lead to a buildup of toxins that can affect the health of the fish. Stress is another common cause of yellowing, caused by environmental changes, overcrowding, or aggression from other fish.

Additionally, certain diseases can cause yellowing in angel fish, such as bacterial infections or parasitic infestations.

Identifying the underlying cause of yellowing in angel fish is essential to address the issue adequately. By taking steps to improve water quality, reduce stress, and treat any underlying diseases, it is possible to restore the health and vibrancy of these beloved aquatic pets.


Possible Causes


When it comes to the yellowing of angel fish, there are several possible causes to consider. Below are some of the most common causes that could be affecting your fish:

Poor Water Quality


Poor water quality is one of the most common causes of yellowing in angel fish. If the water in the tank is not maintained correctly, it can lead to a buildup of toxins and waste products that can harm the fish.

This can lead to various health problems, including yellowing of the skin. Some of the factors that can contribute to poor water quality include overfeeding, overstocking, and inadequate filtration.


Inadequate Diet


Another possible cause of yellowing in angel fish is an inadequate diet. If the fish are not getting the proper nutrients they need, it can lead to various health problems, including yellowing of the skin.

Some nutrients essential for healthy skin include vitamins A, C, and E, as well as omega-3 fatty acids. If the fish are not getting enough of these nutrients, it can lead to skin problems.




Stress can also be a factor in the yellowing of angel fish. Exposure to stressful conditions can weaken the fish’s immune system and make them more susceptible to disease.

Stressful conditions can include overcrowding, poor water quality, and sudden changes in temperature or lighting. If the fish are under a lot of stress, it can lead to yellowing of the skin.




Finally, disease can also be a cause of yellowing in angel fish. Several diseases can cause the skin to turn yellow, including bacterial infections, fungal infections, and parasitic infections.

If you suspect that your fish may be suffering from a disease, it is essential to seek veterinary care as soon as possible to prevent the spread of the disease to other fish in the tank.

In summary, poor water quality, inadequate diet, stress, and disease are all possible causes of yellowing in angel fish. By addressing these factors, you can help to keep your fish healthy and vibrant.



Yellowing of Skin


One of the most common symptoms of an angel fish that is not feeling well is yellowing of the skin. This can occur for various reasons, including stress, poor water quality, and disease.

If you notice that your angel fish is turning yellow, it is essential to determine the cause and provide appropriate treatment immediately.

Yellowing of the skin can be a sign of a bacterial or fungal infection, which can be treated with medication. It can also be a sign of a parasitic infection, such as ich, which requires a different type of treatment.

In some cases, yellowing of the skin may be a symptom of a more severe health issue, such as liver disease or cancer.


Change in Behavior


Another symptom of a sick angel fish is a behavior change. If your fish is ordinarily active and suddenly becomes lethargic or stops eating, this may be a sign that something is wrong.

Other changes in behavior to look out for include swimming upside down, darting around the tank, or hiding in one spot.

Various factors, including stress, poor water quality, and disease, can cause these changes in behavior. It is essential to monitor your fish closely and take action if you notice any changes in behavior.

Sometimes, a behavior change may indicate a severe health issue that requires immediate attention.

In summary, yellowing of the skin and changes in behavior are two common symptoms of a sick angel fish. If you notice either of these symptoms, it is essential to determine the cause and provide appropriate treatment immediately.




Preventing yellowing in angel fish is the best approach to keeping them healthy. This section will cover a few essential prevention measures.


Maintain Good Water Quality


Maintaining good water quality is crucial to prevent yellowing in angel fish. Poor water conditions can cause stress, leading to health problems, including yellowing. The following steps can help maintain good water quality:

  • Test water regularly for pH, ammonia, nitrite, and nitrate levels and make adjustments as necessary.
  • Change 25% of the water every two weeks.
  • Use a good quality filter and replace the filter media as the manufacturer recommends.
  • Avoid overfeeding, as excess food can lead to poor water quality.

Provide a Balanced Diet


Providing a balanced diet is another critical prevention measure. A balanced diet can help keep the fish healthy and prevent yellowing. The following tips can help provide a balanced diet:

  • Feed various foods, including commercial fish food, frozen or live food, and vegetables.
  • Avoid overfeeding, as excess food can lead to poor water quality.
  • Feed smaller portions several times a day rather than one large meal.

Minimize Stress Factors


Minimizing stress factors is also essential to prevent yellowing in angel fish. Stress can weaken the immune system, making the fish more susceptible to diseases and infections. The following steps can help minimize stress factors:

  • Avoid overcrowding the tank.
  • Provide hiding places and plants to create a natural environment.
  • Avoid sudden changes in water temperature or pH levels.
  • Handle the fish with care during cleaning or maintenance.

By following these prevention measures, angel fish owners can help keep their fish healthy and prevent yellowing.


Identify the Cause


Before administering any medication or treatment, it is essential to identify the underlying cause of the yellowing in your angel fish. As mentioned earlier, discoloration could result from various factors such as poor water quality, stress, or disease.

To identify the cause, check the water parameters such as pH, ammonia, nitrate, and nitrite levels. Ensure that the water temperature is within the recommended range for angel fish.

Also, check for signs of stress, such as aggression, hiding, or lack of appetite. If you suspect a disease, observe the fish for other symptoms, such as fin rot, white spots, or rapid breathing.


Administer Medication or Treatment


Once you have identified the cause, you can use the appropriate medication or treatment. Here are some common treatments for yellowing in angel fish:

  • Water changes: If poor water quality is the cause, frequently change water to improve the water parameters. Aim for a pH of 6.5 to 7.5 and ensure the temperature is between 75°F and 82°F.
  • Stress reduction: If stress is the cause, provide a calm and peaceful environment for the fish. Add hiding places like plants or rocks, and avoid overcrowding the tank.
  • Medication: If a disease is a cause, administer medication as a veterinarian or fish expert prescribes. Common medicines for yellowing in fish include antibiotics, antifungal, and antiparasitic drugs.

It is essential to follow the instructions carefully when administering medication or treatment. Overdosing or using the wrong medication can cause more harm than good. If the yellowing persists or worsens, seek the advice of a fish expert or veterinarian.




In conclusion, the yellowing of angel fish can be caused by various factors. It could be due to stress, poor water quality, or genetics. Ensuring the tank is clean and the water parameters are within the acceptable range is essential. Providing a healthy and balanced diet can also help prevent yellowing.

If the yellowing is due to genetics, not much can be done to reverse it. However, it is essential to note that yellowing does not necessarily mean that the fish is unhealthy. As long as the fish is active, eating well, and showing no other signs of illness, there is no need to worry.

Observing the fish closely and monitoring any changes in behavior or appearance is recommended. Regular water changes and proper tank maintenance can go a long way in ensuring the health and well-being of the fish.

Overall, angel fish’s yellowing is uncommon and can be easily prevented and managed with proper care and attention.

Latest posts

  • Are Swordtail Fish Mollies? Differences and Similarities Explained

    Swordtail fish and mollies are two common freshwater fish that are often confused with each other due to their similar physical appearance. While both species belong to the Poeciliidae family, they are not the same fish. Swordtail fish are known for their distinct sword-like tail fins, while mollies have a rounded tail fin. In this…

    Read more

  • Are Swordtail Fish Platies? Understanding the Differences

    No, Swordtail Fish and Platies are two different species of freshwater fish. While they belong to the same family (Poeciliidae), they have distinct physical characteristics and behaviors that differentiate them. Swordtail Fish have a distinct sword-like extension from their tail fin, while Platies have a rounded tail fin. Additionally, Swordtail Fish tend to be larger…

    Read more

  • Can Swordtail Fish Breed with Mollies? Exploring the Possibility

    No, Swordtail fish and Mollies cannot interbreed. Although they are both members of the Poeciliidae family and have similar reproductive strategies, they are two distinct species and cannot produce viable offspring together . However, Swordtail fish and Mollies can be kept together in the same aquarium if their specific environmental and dietary requirements are met.…

    Read more