Why Do Angelfish Eyes Turn Red?

Depending on the type of angelfish, their eyes can turn red as a result of natural development (which is no cause for concern) or due to injury and infection. If your angelfish is not part of the species that naturally have red eyes, the most common cause is stress due to poor living conditions. 

The biggest concern we have now is to know the difference. When should you be worried about your angelfish developing red eyes, and what are the precautions you can take to prevent, or solve, the development of red eyes due to injury and infection?

Is It Natural For Angelfish To Have Red Eyes?

Most angelfish are bred and collected mainly due to their visual features. As a result, various breeders have manipulated the genes and breeding patterns of different types of angelfish to create unique-looking ones.

Selective breeding among angelfish is quite common. Besides the eye color, various other attributes, including stripes, spots, and the color of their gills and body, are altered for unique looks without causing a weaker and ‘sicker’ breed.

Therefore, although angelfish in the wild might not necessarily have noticeable red eyes, it’s a common genetic modification among breeders. The most popular angelfish known for their red eyes are the ‘Silver Angelfish’ and the ‘Zebra Angelfish.’

In the specific case of the ‘Zebra Angelfish,’ blood red eyes is a positive sign as it indicates good health and full maturity.

It’s important to note that not all of these types of angelfish, who generally have red eyes, develop the proper color for an attractive visual feature. This color deficiency is also nothing to be worried about as it only indicates a lack of pigmentation due to weak genetics and is not a sign of ill health.

Dark Angelfish

When Should I Be Worried About Red Eyes On My Angelfish?

Suppose your angelfish was not breaded to develop red eyes, and your mature angelfish suddenly developed red eyes within a few days of careful observation. In that case, you will need to check their general health as this indicates an illness or issue.

However, the solution is not quite simple as there are various reasons an angelfish will develop red eyes. The most common problematic reasons an angelfish develops red eyes are stress, injury, or poison.

Stress Can Cause Angelfish’s Eyes To Turn Red

Stress is the most common reason angelfish eyes turn red as it affects their general well-being by breaking down the immune system. However, stress is a universal issue among angelfish that can be caused by different reasons.

Various disturbances in their habitat can result in them developing red eyes, but stress also causes other behavior, which makes it easy to diagnose.

For example, fish who are stressed tend to eat less, might also develop white spots, and swim in non-pattern-like sequences.

The following are the most well-documented cases regarding causes of stress:

  • The water quality and conditions are paramount, and failing to meet the basic standards will cause stress among angelfish. This includes incorrect pH levels, water temperatures that are either too hot or too cold and inadequate oxygen levels.
  • Territorial violence among angelfish is also not unusual, and as a tank becomes more overcrowded, they will start to fight to assert their dominance. Not only are angelfish prone to violence because of territory, but they will also be more aggressive as a couple once they start mating.
  • Feeding angelfish is also tricky to manage as there is commonly an issue with overfeeding or underfeeding. Either mistake in feeding will cause malnutrition resulting in high levels of stress.
  • Moreover, sudden movements, loud noises, and constant disturbances during any time of day will cause stress among angelfish as they never quite know what to expect. Some angelfish are constantly under pressure due to an unideal tank placement; therefore, ensure that your aquarium is placed somewhere peaceful and quiet.

Poison Can Cause Angelfish’s Eyes To Turn Red

Poisoned water quickly affects angelfish as they are constantly exposed to the same water. If an immediate solution is not created to rectify the issue, severe results like internal and external bleeding will occur.

For example, decomposed materials in tanks like plants and food result in a build-up of bacteria if the habitat is not cleaned properly. The combination of Nitrogen and hydrogen in the tank also creates an inorganic compound known as Ammonia.

Although Ammonia is not uncommon in tanks, high levels of it attack the cells causing bursting and bleeding around the eyes.

In addition, a build-up of Ammonia without natural bacteria to stabilize the levels will result in nitrite. Although not as harmful as high levels of Ammonia, it still affects the blood, which may lead to the cells bursting around the eyes.

Similarly, a build-up of carbon dioxide also affects the immune system of an angelfish as an increase in gas without a natural stabilizer causes a deficiency in the development of blood cells.

It’s important to note that the above-mentioned toxins are commonly found in aquariums but at acceptable and appropriate levels. An extreme increase in these toxins is usually caused by mistake or neglect, but they have a tremendous impact on the well-being of the angelfishes.

Injury Can Cause Angelfish’s Eyes To Turn Red

Another cause of bleeding around the eyes is due to injury. Owners can accidentally harm the vessels around the eyes when moving the angelfish to different habitats or handling them during breeding.

Often the vessels will be damaged but only slowly start bleeding over time, resulting in an unexpected red eye upon the next observation. Similarly, angelfish which are aggressive towards one another, can cause injury to the body and often attack the face causing bleeding around the eyes.

What Should I Do If My Angelfish Eyes Turned Red?

The difference between a ‘red eye’ as a result of pigmentation and genetics looks quite different from a ‘red eye’ due to damaged vessels and bleeding.

As a result, if there is no red coloration around your angelfishes’ skin and the socket around, or even in the eye, has bursts of redness, then you’ll have to take the necessary precautions to find a solution.

Stress will be difficult to eradicate as you will need to find the source first.

However, once you have identified the source, removing it will restore order in the habitat resulting in the angelfish becoming calmer and their cells and immune system functioning normally.

Water that is poisoned will be hard to rectify, but it’s easier to prevent. Ensure that you regularly test the water’s quality and keep a disciplined schedule for cleaning and maintaining the aquarium.

However, don’t use chemicals to thoroughly clean the habitat as angelfish require a small amount of bacteria to stabilize their environment. In addition, ensure that the filter system is functioning correctly without excess filth and add air stones to balance the Co2 levels.

Finally, adding a small amount of Epson salt to the tank won’t cure injuries around the eyes, but it will ease the inflammation and swelling as it heals over time.

Angelfish with Blurred Background


Angelfish like the ‘Silver Angelfish’ and the ‘Zebra Angelfish’ are breaded with the intention of an attractive red color pigmentation around the eyes; therefore, it’s not an uncommon feature among them. However, if the redness is caused by damaged vessels around the eyes, you need to deduce the cause of the issue (injury/poison/stress) and treat it accordingly.