Why Is My Cardinal Tetra Turning White?- Answering Your Queries

The cardinal tetra is a lovely freshwater fish primarily present in North America, where it lives in the slow-moving waters of ponds and small streams. You can quickly identify them by their bright red color and beautiful horizontal stripes. But this vibrant coloring can change as your fish grows older. Sometimes you might even notice your Cardinal tetra turning white. Do you know why?

There are many reasons why your Cardinal tetra is turning white. Some of them might be stress, bright light, diet, even illness, change in water parameters, and parasites. To determine which one applies, we’ll need to figure out the cardinal tetra’s life stage and identify any other issues that may be taking place in its tank.

This article will talk about the most common reasons your tetra is turning white and how to fix these issues.

How Does Cardinal Tetra Look Like?

Cardinal tetras are part of the characin family. They have a dark body with red stripes on their sides, head, and tail. Their fins are orange in color, while some may turn yellowish-orange when they reach maturity.

Cardinal tetras have a relatively small size which makes them suitable for smaller aquariums. Males are usually larger than females. But their body is slimmer and more streamlined, so they can dart quickly through the water column to catch prey or avoid predators. Females, on the other hand, tend to be longer with bulkier bodies.

Do Cardinal Tetra Change Their Color?

Cardinal tetras sometimes change color over time. This is not unusual, especially if it is in their best interest to do so. However, this color change can be troublesome for fish owners who want their pets to remain colorful and vibrant.

Most fish can change color for a variety of reasons. The most common cause is to camouflage themselves from predators or prey. Sometimes, you can do this simply by changing the colors on their bodies, which doesn’t affect the cardinal tetra’s shape. Other times, they will try to mimic another species to better blend in with their surroundings.

Another reason cardinal tetras can change color is due to an infection or illness they are suffering from, such as ichthyophthirius (also known as “ick”). This disease causes the fish’s body and fins to appear yellowish, making its scales look like tiny white dots.

Why Is My Cardinal Tetra Turning White?

Cardinal tetras are a prevalent fish of choice for many aquarium hobbyists. However, novice aquarists often misunderstand their coloration and frequently assume it as an indication of sickness. They come in vibrant red color with black polka dots on the top half of the body and an iridescent white bottom, which looks beautiful when swimming together in an aquarium.

Some of the reasons why Cardinal tetra turns white are:

Improper Housing

They need a broad and shallow tank to thrive, not too long or tall. It is also important to avoid sharp angles and corners as this would make them feel threatened. Adding live plants in the aquarium can provide good hiding places for cardinal tetra fish, making it more comfortable for them while swimming around freely.

Plants also help clean the water and keep it well oxygenated, essential for healthy cardinal tetra fish.

High temperatures

Keeping your aquarium warm would kill off all of your hard work in caring for them. But, unfortunately, it also puts stress on the fish and causes their immune system to weaken, making them susceptible to diseases. The recommended temperature range for cardinal tetra fish is between 72°F and 81°F.

Poor Water Quality

Cardinal tetras are a susceptible species that cannot tolerate poor water conditions. Make sure you have high-quality filters in your aquarium to keep the water well oxygenated, clean, and free of harmful chemicals or waste products.

Poor Nutrition

Providing your cardinal tetra with a balanced diet would ensure their health and coloration. There are many healthy food options for them, including high-quality flake foods, frozen or live worms/insects, crushed spirulina tablets (get at any pet store), and freeze-dried brine shrimp, to name a few.


There is a possibility that your cardinal tetra has injuries in one way or another. This could be due to aggressive tankmates’ attacks or injuries while cleaning the tank. Regardless, if you see any cuts on their bodies, it is important to keep them separated because they are susceptible to infection.

Sudden Lighting

This is a relatively uncommon reason for the color change of your cardinal tetra. Still, it may be possible that one day you suddenly start seeing them turn white overnight without any warning signs. There could be something wrong with your light, so try changing it or check if some debris has accumulated near it and remove it immediately.


Many types of illness could affect your cardinal tetra fish, such as constipation, dropsy (bloating), ichtyopthirius/Ick disease, fin rot, ulcers on the body, or mouth, etc. Anyone or more of these symptoms can cause your cardinal tetras to turn white.


Inbreeding can lead to health issues and color abnormalities. For example, Cardinal tetras have a limited gene pool because it allows only recessive genes to manifest and express themselves. Therefore, if you breed two closely related fish, they are likely to have color abnormalities or deformities in their offspring because of the limited gene pool.

Chlorine Poisoning

Chlorine can be toxic at extremely high levels. So treat your tap water with a water conditioner that removes chlorine and chloramines before you add it to your aquarium. This will prevent any adverse effects on the cardinal tetras in your tank.


Sometimes during transportation, fish can experience shock, which is not easy for them to adapt to. Especially if they are in contaminated water or there was a significant change of temperature during the trip.

You may not see it, but your fish feel this stress, and their immune system becomes weak. As a result, they are more susceptible to diseases that you could avoid otherwise.

How To Stop Cardinal Tetra From Turning White?

Cardinal tetras usually live in schools and are easy to identify as they have red fins. They are vibrant fish, and owners love them for their beautiful body color. So it will break the heart of the owner when they see their beloved fish losing its color.

So, some of the ways that can help you stop Cardinal tetra from turning white are:

Get Bigger Fish Tank

Cardinal tetras are very small, and they need a bigger tank. It would be best if you kept them in groups of five or six. This helps to stop them from turning too pale.  It is hard for them to compete with other fish when there aren’t enough members in the group.

These fishes like keeping close together, but this can cause them to turn white. This is because they need more space, and a good number of them can help keep their color better as they will not feel threatened by other fish.

Add Some More Background

Cardinal tetras do well with live plants, but this might make it difficult for you to see their beautiful red fins. Adding some rocks or driftwood in the back of the tank will make them feel more comfortable and adjust their color well.

Cardinal tetras like living plants, but you should use Mopani wood if you cannot keep real ones in your fish tank. They love to hide behind it, which will help them stay red.

Monitor Water Quality

You should continuously monitor the quality of water in your fish tank. If any nitrates or other chemicals can change their color, you should keep them under control by frequently changing the water and adding some safe additives to it. Also, do not use tap water for aquariums as they contain chlorine harmful to your fish.

Monitor Temperature

Cardinal tetra is a tropical fish. So, it would help if you kept them in water with temperatures between 72-81 degrees Fahrenheit. This will help them stay healthy as well as maintain their color better. However, they don’t do too well when there are sudden changes in the surrounding environment, so you must keep an eye on the water temperature in their tank.

Make Sure You Feed Your Cardinal Tetras The Right Food

Cardinal tetras are omnivorous fish. Hence, you need to feed them with both plant matter and animal food. You should always provide them a high-quality flake or pellet food with plant material so that their color does not change much.

Adding foods rich in color enhancers like brine shrimp and frozen daphnia to their diet will also help them stay red.

Add Some Salt

Adding some salt to the fish tank can reduce stress and keep your cardinal tetras healthy too. It is safe for your aquarium as long as you add it in a small amount that does not exceed one teaspoon per five gallons of water.

Give Your Cardinal Tetra Some Sunlight

Cardinal tetras need sunlight that will enhance the colors of their fins. However, it would be best if you kept the top of the tank. It ensures that your fish does not jump out and die due to a lack of oxygen.

Always Be Patient

Even though owners can quickly identify the color change in their fish, they need to understand that there are various certain reasons why cardinal tetras lose their color. Therefore, you should always be patient and wait for the fish to restore its natural redness.

If you follow these simple steps, your cardinal tetras can turn back their beautiful colors quickly in no time.

Some FAQs

How Long Will It Takes For My Cardinal Tetra To Get Back Its Vibrant Color?

It can take anywhere from a few days to more than two weeks for your cardinal tetra fish to get its color back. Therefore, a healthy diet of high-quality food is critical, as are sufficient water changes and enough time outside the tank for exercise.

Keep an eye on it during this period, watching closely for any signs of distress or illness. If there are none, chances are it will soon be back to its usual self!

What Happens If My Cardinal Tetra Does Not Get Back Its Vibrant Color?

If your cardinal tetras don’t get their color back within two weeks, you may have a sick fish on your hands. The fish change color in normal conditions, and it will return to normal.

But you need to be watchful if there are no signs of recovery after a week or so. It would be best if you took your fish to an aquarium professional for treatment.


Summing up, there could be many reasons for your cardinal tetra to turn white. If you find that your fish’s color is changing, you should consider all these possibilities and take immediate action if necessary.

Do not forget to take good care of your cardinal tetra fish. This way, it will stay healthy and beautiful for an extended period!

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