What Is The White Stuff Growing In My Cardinal Tetra?

Even though Cardinal tetras are hardy fish, you can never keep them away from the different health issues that result in community fish. Moreover, these fish lives in schools or with many other fishes of different species. Thus, they will get more exposure to different types of infections and diseases. Have you ever wondered why there is white stuff growing in your Cardinal tetra?

The white stuff growing in Cardinal tetra is not an uncommon problem. Ich is one of the reasons behind it. Ich is a common disease that affects the fish, but only if they are weak and have a compromised immune system. It will be better for you to treat your fish with an anti-bacterial remedy just in case because there could also be another infection going on aside from Ich.

This article will learn about what causes it and how to treat them on time for a healthy aquarium.

What Are The White Spots In Cardinal Tetras?

Cardinal tetras are beautiful freshwater fish that have been popular in the aquarium industry for years. However, one problem with these little guys is what many people call “white spots” or “cotton candy.” These white crystals, which look like tiny cotton balls growing on your cardinal tetra’s body and fins, are not harmful to them but can become a nuisance.

Usually, the white spots growing in Cardinal tetras are is a sign of disease -Ich. This is a common disease in aquarium fish and other water-based creatures. In Ich, you will notice that the white spots grow into white tufts that are very noticeable on the fish. This disease occurs due to a parasite, and these parasites destroy tissue in your Cardinal tetra’s body while they take away his food source. The reason why this happens so fast is because of their rapid reproduction rate.

The Ich life cycle is fascinating once you’ve seen it in action. Still, the sad part about this parasite is that if it goes unnoticed for too long, your Cardinal tetra will eventually die from starvation and tissue damage to his body. On the other hand, the lifespan of a cardinal tetra without treatment can be as short as three days. However, if you kill the Ich parasite before it reaches its complete life cycle, your fish will live a long and healthy life.

What Are The Causes of White Stuff Growing In Your Cardinal Tetra?

There are many possible causes of white stuff growing in your cardinal tetra. Understanding what is causing it to grow can help you treat your fish or know how serious the situation is.

The most common causes of white stuff in cardinal tetras are:

Change In Water Parameters

If the water parameters of your fish tank change suddenly for whatever reason, it can cause white stuff to grow on cardinal tetras. The most likely culprit is usually a sudden temperature change, but other factors could be responsible too.

Poor Water Quality

Poor water quality is the number one reason why fish get sick. So this should be your first suspect if your cardinal tetra begins showing signs of ill health, like bits of white stuff growing on them.

Water Temperature

If the water in your tank is too cold, it can cause fungus to grow inside cardinal tetras. This is because their immune systems will not be as effective at fighting off any infections that may arise from the growths in the cold water.

Nutritional Deficiencies

Another possible reason for bits and pieces of white stuff growing on cardinal tetras is a lack of proper nutrition. If your fish lacks the nutrients they need, their immune systems become weak, and fungus can grow more easily inside them.


It would be best if you always kept Cardinal tetras in groups of at least five but ideally ten or more because it makes them happier and less susceptible to sickness. On the other hand, if you have more cardinal tetras than recommended, it can cause a lot of stress and weaken their immune systems, making them way more likely to get sick from fungal infections.


Keeping your water clean with chlorine is important for all fish, but if you have too much in there, it can start causing health issues that make cardinal tetras more susceptible to fungal growths on their bodies.

How To Know The White Stuff Growing In Cardinal Tetra Is Ich?

The white stuff growing in cardinal tetra is Ich. This disease, also called Ichthyophthirius Multifiliis (Ich), needs immediate treatment, or the fish will die. However, some of the symptoms that prove the white stuff growing in Cardinal tetra is Ich are:

  • Fish becoming lethargic and swimming less. These symptoms are the first sign that you need to treat Ich in your Cardinal tetra immediately.
  • A white film on top of the fish’s body, typically caused by a fungus infection and sometimes Icthyophthirius Multifiliis (Ich), causes this film.
  • Fish are becoming pale, and the skin appears to be decaying rapidly due to a bacterial infection from an Icthyophthirius Multifiliis (Ich) infestation.

Are The White Stuff Growing In Cardinal Tetra Serious Problem?

If you notice a white cloud in the tank where your cardinal tetra lives, it is difficult not to be concerned. It can look like mold or some other type of infection that requires immediate attention.

However, there are certain circumstances when this is normal and will go away. Such conditions are:

Bacterial Cloud

If the white cloud is some bacterial growth, it is not unusual. Usually, this type of infection will dissipate with time as long as the fish are healthy and have an excellent immune system. The problem occurs when there isn’t’ enough oxygen in the tank or conditions aren’t just right. This can happen with overcrowding or other factors.

Normal Spawning Behavior

This seems to be a genuine concern, but if there are eggs in the tank and you see a white cloud around them, this is normal spawning behavior for cardinal tetra fish. The males will fertilize the eggs, so they stick to plants or objects on the bottom of the tank. Once the eggs fertilize, a white cloud forms around them as they grow and develop. This is perfectly normal, so don’t’ worry about it being an infection or anything dangerous to your fish health.

Injury And Fin Nipping

If the white cloud appears on one of your fish instead, you should look at them carefully. The first thing is whether or not they are still eating and acting like normal. If so, this type of infection will usually go away by itself if left alone for a few days. There may also have been some injury from fighting, another fish nipping at them, or something else that happened. This, too, will usually go away in a few days if left alone.

If there are clear signs of injury or bacterial infection, you should proceed with care and contact your local pet store for more information about treatment options. The best thing to do is monitor the cardinal tetra carefully and see what it does.

How To Treat White Stuff Growing In Cardinal Tetra?

One of the common problems in cardinal tetras is white stuff growing on their bodies.

When your fish has this issue, the first thing you should do is to search for other symptoms like behavior issues or skin damage, etc. If there are any such signs, then it is better to go for a complete diagnosis.

Some effective treatment methods for the white stuff growing in Cardinal tetras are:

Treat The Water

Water quality is the first thing that you should look into. If your tank has poor water conditions, then it can lead to this problem.

To treat the water, you need to increase the temperature of the aquarium (preferably 84-86 degrees Fahrenheit) and provide a good amount of dissolved oxygen in the tank for optimal fish health.

Increase The Lighting

This problem can also arise due to the insufficient lighting in your aquarium. To treat this issue, you need to increase the intensity of light (at least six hours a day) and provide high-quality food for your fish.

Clean Your Tank Regularly

It is necessary to clean your tank at least once in two weeks. You can also use a gravel siphon while cleaning the tank for better results.

You should change around 20-25% of the water weekly. Also, make sure you don’t forget to dechlorinate the new water before adding it to the tank.

Remove The Fish From Tank

You can remove your fish from the tank for around 15-20 minutes and use a soft brush or sponge to clean its body correctly. Also, make sure you don’t forget to put them back in the water after cleaning.

Decrease Feeding Rate

Sometimes overfeeding is also a significant reason for this problem. To treat it, you need to decrease the amount of food and increase the frequency so your fish can get rid of excessive nutrients from its body.

Increase The Ammonia Level

Sometimes a high ammonia level in water is also responsible for white stuff growing on cardinal tetra’s skin. In such a case, you need to increase the ammonia level of water and clean it with a good filter.

You can also use Tetra EasyStrips for checking your fish’s health regularly. It is an effective product that not only shows you whether your fish has any issue but also pinpoints the exact place where there’s something wrong in their body.

You can also ask for a complete diagnosis from your local fish store and follow their instructions to eliminate the white stuff growing in cardinal tetra’s skin.


In conclusion, the white stuff growing on Cardinal tetra could be Ich or velvet, and both of them are very deadly to fish. So if this happens to you, this is how you can deal with these two problems.

If Ich

  • Buy a tank that is at least 30 gallons.
  • Do a 100% water change every day for about five days
  • If you still see Ich on the fish, do another 100% water change and add some aquarium salt. The amount should be one teaspoon per gallon of water. If this does not work after two more times of changing out all of the water and adding in salt, try treating your fish with ich medication.

If Velvet

  • Do a 100% water change.
  • Make sure all of your tanks’ stats are good (ammonia, nitrate, etc.)
  • Buy aquarium salt made for freshwater fish at any pet store
  • Buy some medication that treats velvet at any pet store. Follow the instructions on the back of the package to determine how much salt and medicine your tank needs.

Please let me know if I missed anything. Thanks for reading my blog post. You can also contact me if you have any questions.

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