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The Cardinal Tetra is a freshwater fish that can survive in any aquarium. This fish contains a bright coloration and does not need a lot of effort to take care of. This fish is scientifically referred to as Paracheirodon axelrodi. The breeding of these fish, just like their relatives Neon Tetra, has grown in captivity, and this has led to increased numbers in the aquarium industry.

User:Lerdsuwa, CC BY-SA 3.0, via Wikimedia Commons

In addition to the ease of taking care of this species, they are also peaceful. In the natural habitat, this species forms large groups that create schools of moving color. This species lives in most parts of South America, and they are more spread in Orinoco and Negro Rivers. Being schooling fish and bearing in mind their peaceful nature, this species can do extremely well in a community tank.

Also, there are some of the aspects of taking care that is unique from the other species from their family, and that is why it is important to learn about their care. This guide will, therefore,  enable you to learn all the fundamentals of taking care of this species that you need to know before buying this species. They range from diet, tank conditions, water, and breeding.


Scientific NameParacheirodon axelrodi
ColorBlue stripes on a red body
Size2 inches
LifespanUp to 5 years
Care LevelEasy
Tank Size10 gallons
Freshwater or saltwaterFreshwater
Temperature73 to 81 degrees F
CompatibilityPeaceful community


The Cardinal Tetra is a peaceful fish that does extremely well in a community tank. When it comes to the ideal tank for this species, there are many choices to make. However, the first rule is that any aggressive, even the slightest, should be avoided. Any territorial species will bully this fish and stress them. The Cardinal Tetras are so delicate, and they are not good at defending themselves, and it is best to keep the environment peaceful.

This species is small in size, and therefore you should avoid keeping them together with large fish that might eat them. This applies to even the peaceful species. They might be non-aggressive and still eat the Cardinal Tetras due to their small size.

Some of the ideal choices for tank companions include;

  • Guppies
  • Hatchet fish
  • Zebra Danios
  • Ember Tetra
  • Back Skirt Tetra
  • Mollies
  • Green Neon Tetra
  • Chili Rasbora
  • Emperor Tetra
  • Harlequin Tetra


This species does not thrive alone but prefers living in groups. In order to bring out their natural behaviors, you should keep them in groups of at least 6. The bigger the group, the more active and happy they will be.


User:CTho, CC BY-SA 2.5, via Wikimedia Commons

Most aquarists confuse the Neon Tetra with Cardinal Tetras. The main attraction to this species is their color. The fins do not attract attention since they are small. They have bodies that are typically red and blue. A stripe runs along the lower side from the head to the tail, and a blue stripe just sits on the top. They have brilliant and vibrant colors, and therefore a shoal can be a striking sight.

The main difference between the Cardinal and Neon Tetra is the length of the stripe. For the Neon Tetra, the red stripe only darker the body halfway. The fish of this species are transparent with a white belly. Despite being colorful, sometimes there is some variation in coloration that appears, such as silver and gold, but this happens in rare cases.

It is a bit challenging to tell the difference between a male and female Cardinal Tetra since they have similar coloration. However, you can identify the female when they are carrying eggs since they have a rounded belly. There is no need to sex this species since they are kept in a large group, and they will most likely pair themselves.


The Cardinal Tetra is not a big fish since they grow to an average size of 2 inches when fully grown. This places them under the small freshwater species that can be kept in a small tank.


In captivity, this species lives for up to 5 years under optimal care. The main factors that determine the lifespan are the water condition in the tank and the diet you are feeding to this species. If you provide the right water parameters as recommended and the proper diet, your Cardinal Tetra is like to reach the optimal limit of the lifespan. In the wild, it is difficult to attain this age since they have many challenges such as the threat from predators’ poor diet, and sometimes water conditions may change. They, therefore, live for an average of one year.


This species is a native of riverbeds of Orinoco River to the Amazon River tributaries referred to as Rio Negro in South America. It is found in some parts of Brazil, in particular, Manaus and in the western half. It has also been discovered in parts of Western Colombia.

They prefer swimming in upper streams in the canopies. They are fast swimmers, and therefore they need an open space. Their natural home specifically consists of tributaries or the flooded areas of the forest. This species loves water that is crystal clear with some nice vegetation over. The vegetation is important since it provides some hiding spots whenever the species feel unsafe or under attack from predators.


The Cardinal Tetra is flexible in nature and easy to take care of. They are less demanding compared to most species, and this makes them an ideal choice for beginners. As long as they are left in good condition, they can survive for long without needing a lot from you. They are shoaling fish, and they, therefore, thrive in groups of maybe as many as six. You will most likely find them swimming in the middle or upper section of the aquarium.

This species loves peace, and they love living with their own species. They become more active and confident. It is therefore not advisable to keep them alone since this might cause them stress. They will lose color and have their health affected if they are left alone and stressed. Generally, their behavior is positive, and this makes them the ideal addition to your aquarium.


As stated earlier, this fish does not require a lot of effort to take care of. In the wild, they live in soft, slightly acidic, and warm temperatures, but they can tolerate a few changes in these parameters. The captives one is flexible to a newer environment. Below are some of the conditions that should be maintained for your fish to live comfortably and happy;


This fish is a schooling species, and therefore they need a tank with enough space for them to swim together. You need a tank of at least 15 gallons. This tank should be at least  3 feet long and  2 feet wide. If you are planning to keep more fish, you will need a bigger tank. Generally, the tank sizes will be determined by the number of fish you are putting in.


The tank needs a filter. You can opt for any mechanical filter as long as it does not have high-speed water flow. This is because, in the wild, the Cardinal Tetra lives in a calm, steady low-speed water flow. The filter you choose should have all the filter media in it. By adding a canister filter to your tank, you will increase its volume. Also, the filter being big, will house many of the beneficial bacteria in its biological media that will be helpful in maintaining your aquarium water.


This species rarely swim at the bottom of the tank, and for this reason, they do not have a preference for a substrate. If you are using black water, ensure that you use a white color substrate. This makes it more appealing. For the other water, you can go for a dark substrate. If you are planting some live plants, then the substrate must be able to support the growth of roots.


Lighting should be dim if you are using black water. The floating plants will replicate their natural habitat as if the sun rays are entering the tank. The body color will be brighter and more vibrant in dim lighting.


As stated earlier, the water in the natural habitat is usually warm. There is, therefore, a need to replicate that in captivity, and this should be kept constant. You will therefore need a heater to warm the water whenever it drops below the limit. Use a thermometer to keep monitoring the temperature.


In order to mimic the natural habitat, you need to add a few decorations such as plastics. The tank should be kept planted since this is what this species prefers. If you are using black water, the ideal plants include the java fern,  anubias, and amazon sword, and this can be combined with some floating plants such as amazon frogbit or gnat duckweed. You can also add some driftwood as well to create more hiding spots. These hiding spots serve as hiding places whenever they feel stressed or under threat.

If you want to go for an aquascaped tank, you have a number of plants to choose from. However, the decorations should not have sharp edges and be rough-surfaced since they might injure the species.


The Cardinal Tetra prefers medium vegetation. The tank should not be over-planted since they also need enough space to swim.


This species does not need a strict regular cleaning of the tank. However, this does not mean that the tank should not be cleaned from time to time. This is important to maintain the cleanliness of the tank and prevent the spread of diseases.


When it comes to life and survival of the Cardinal Tetra, the water parameters are the most important factor. More so, in the aquarium setup, the water conditions must be adhered to strictly. Therefore, below are some of the parameters that your tank water should meet;


This fish resides in warm waters in its natural habitat. This needs to be replicated in captivity. The ideal water temperature should be between 72 to 82 degrees F. In the natural habitat, the water is usually towards the upper limit, and if you can be able to maintain to the upper limit, then that will be better for this species.


The average PH level should range between 4.0 to 6.0 for the sake of quality care. It is crucial to ensure this remains within that same range, and this will save the Cardinal Tetras from stress and keep them healthy.


The water hardness should be maintained below 4Dgh and dGH of between 2 to 10 degrees.


Although the other varieties of Tetras might have mineral requirements, this species does not have specific mineral requirements.


It is important to change the water in the aquarium on a regular basis so as to remove ammonia and nitrites. These minerals are toxic to fish. Ammonia is produced in the tank in two ways; one is when the fish release their waste more than the rate at which beneficial bacteria changes to nitrate.

Despite the type of water you are using in your aquarium, you can replace about 50 percent after every week. Before changing, ensure the water parameters of the new water you want to put in the aquarium are up to the standard. The amount of water you are changing depends on the number of fish in the tank and the size of the tank. If you have a heavily planted tank well stocked with fish, it is important to change about 50 percent every week.

If you have a larger tank of about 30 gallons and above with 6 to 10 species, then you can change the water once in around three weeks. Monitor the water parameters and use them to determine your own routine of how often you will be doing changes.


Cardinal Tetras are known to be scavengers. They can eat anything that is made available to them.  They are omnivores in nature.  In their natural habitats, they feed on worms and small crustaceans. In the aquarium, they will accept fish live food or regular flake food. This fish is not picky, and they will be happy as long as they are fed on a regular basis.

The Cardinal Tetras are supposed to be fed three times a day. You should ensure that you feed them enough food that they will be able to complete in three minutes. Remember that they are small in size, and they can only eat a small amount. Feeding them for more than 3 minutes will end up overfeeding them. After feeding this fish for 3 minutes, ensure that you remove any uneaten food in the tank since they can fall at the bottom of the tank and rot.

These species need a high content of vitamins, and this should always be in your mind as you decide on what food to feed them. If you decide to feed them on flakes, then you need to go for the highest quality flakes so as to provide your fish with what they need. It is advisable to go through several types of flakes or mix them together. By using several types of flakes, you make It more likely your fish will have all the nutritional needs it requires.

Another great option is using live or frozen foods. This can include some vegetables. All you need is to ensure that you chop them up into small pieces that are small enough for this species to eat without any difficulty. When choosing live foods, the ideal choices include mosquito larvae, daphnia, and brine shrimp. This species is also known for feeding on worms such as bloodworms.

Some of the ideal foods include;

  • Black worms
  • Adult brine shrimp
  • Bloodworms
  • Daphnia
  • Mosquito larvae


It is difficult to tell the difference between the male and female Cardinal Tetra based on their color since they look alike. However, they can be separated by their body patterns and structures. The males have a slimmer body compared to the females and have a hook sticking out from the tail fin. 

Females generally have a larger body since they carry eggs. Due to this big body, if you observe closely, you will notice the bending of blue red stripes on the female’s body.


The process of breeding this species is hard. In the past, a few breeders have made it, but lately, they have been able to. After identifying the breeding pair, you will need to move the breeding pair to a different breeding tank so as to prevent the fries and eggs from being eaten. Their eggs are usually scattered. For breeding, you need to set up a tank that adheres to all the parameters. I.e., PH, temperature, lighting, hardness, and plants.

The Ph. of the tank should be 6.5 and below, more acidic that this will be better of. You should ensure there are floating leaves in the tank so as to dim the excessive light and provide a shade. Ensure that you have something to separate the upper section of the tank from the bottom so as to protect the eggs from the parents. Spawning usually occurs during the evening and night.

During pairing, add the fastest female and the brightest male and ensure the tank conditions are all set. The females will allow the male to swim alongside her. They will mostly swim around the plant. The females release the eggs in the tank, and the male then releases the sperm. They lay an average of 100 to 500 eggs.

After spawning, the parents should be moved back to their original tank. This will give the eggs and fries an opportunity to grow without having a threat of getting eaten by the parents.

The fries are very sensitive to any change in water conditions, and therefore you should closely monitor them. Also, ensure that you use the right filters since they might suck the fries inside it, and this will lead to death. It is important to have air pumps so as to enable the circulation of water and oxygen. Do not stress the fry by providing speedy water and inconsistent water parameters.

After the eggs have been laid, they take 48 to 72 hours to hatch. Within a period of 4 to 7 days, the fries will be free swimmers. They are very sensitive to light at this point, and therefore the aquarium should be dimming as much as possible. After hatching, you should not be in a hurry to feed them since they have their York sac that they feed on for 3 to 4 days. Thereafter you can feed them on infusoria food for the first three weeks.

As they grow older, you can now start providing them with adult food. This food should be broken into smaller pieces for easy feeding. The food should be high on proteins o support their development. If you notice some resistance to eating the adult food, you can feed them on infusoria, then later try feeding them on adult food. They will resemble the adults after 8 to 12 weeks, and they will start o form vibrant blue and vivid red colors. The females will be mature enough to breed at around nine months. They will start laying eggs then.


The Cardinal Tetra, just like the other freshwater species, is prone to diseases. These diseases are mainly caused by poor water quality and a poor diet. If you feed them on the right nutritious diet and ensure water is clean and healthy, you can be assured of a healthy Cardinal Tetra. Some of the diseases include;


This is one of the common diseases which are caused by a parasite known as Pleistophora hyphessobryconis. This parasite is mainly found in live dead or feedable fish in the same tank as the healthy ones. Some of the symptoms include; Lumpy body, loss of coloration, bloating or fish lot infection, swimming difficulties, cysts in the muscles, curved spines.

Other than the above signs, it is easy to notice when your fish is sick or affected by just paying close attention to its behaviors. A sick species will change its normal behaviors. For instance, the fish will no longer be grouped as usual. Also, the swimming will start becoming irregular and sloppy. The affected muscles or tissues will begin to appear pale on the white side in which the disease has progressed.

There are some common means of treating these infections and diseases. In some cases, the fish is just put to rest or euthanized. There are some of the actions you can take in order to save the remaining fish in the tank;

  • Preventing any form of contact between the infected fish and the other fish. This is by putting them in a separate tank.
  • Getting rid of dead fish.
  • Changing and filtering the water properly after moving the infected fish from the aquarium.
  • Quarantine the fish after noticing sickness signs and before adding a new fish in the tank.


IS the Cardinal Tetra a freshwater species?

Yes. Cardinal Tetras are freshwater, and they originate from riverbeds of the Orinoco River to the Amazon River tributaries referred to as Rio Negro in South America. They prefer swimming in upper streams in the canopies. 

Can I keep my Cardinal Tetra Alone?

Yes, you can keep them, but they are naturally schooling species. They thrive best in a group, and they will be more active and happy in a group. By keeping them alone, they will be dull and will end up getting stressed, and this will affect their health.

Are Cardinal Tetras Fin Nippers?

Yes, these species are usually finned nippers, and this mainly occurs as the fish are chasing one another. This species might also nip other fish within the same tank. However, note that not all Cardinal Tetras are fin nippers; it all depends on the fish you have.

What is the cost of buying Cardinal Tetra?

This varies depending on the fish state, the seller you are buying from, and the type you are buying. For instance, an Albino species is cheaper since it is not preferred by most aquarists. However, the average cost of this species is between 1.5 to 3 dollars.


Cardinal Tetras are vibrant tropical fish that are easy to maintain and feed. They are peaceful and are compatible with most species. The interesting and attractive coloration makes them every aquarist favorite. They make the appearance of the aquarium stand out. This becomes more interesting as they swim together in a school.

 This is one of the must pick for every aquarist since you need no prior experience to take care of this fish. All you need to observe is every condition stated, and you are good to go. It is our hope that this guide has given a wide and clear insight into what the care of this species looks like. You can now get yours, and you will never regret the choice.

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