Cardinal Tetra: Tank Setup, Care Guide, Breeding And More… is supported by our readers. When you buy through links on our site, we may earn a commission.

If you are a beginner aquarist, the Cardinal Tetra is the perfect starter fish for your tank. They are among the easiest freshwater fish to care for, being a healthy and hardy species.

Vibrant coloring will make them stand out from the other fish in your tank, whereas a school of them will be absolutely mesmerizing to watch, with their neon coloring and synchronized movements, darting around your tank. 

The Cardinal Tetras are quite popular with the aquarium hobbyists, and as a result, you will see them in community fish tanks more often. 

Although easy to care for, this guide will teach you all you need to know about their diets, habitats, tank mates, and illnesses, plus much more.

Cardinal Tetras (Paracheirodon axelrodi) are part of the Characidae species family. Being very similar to the Neon Tetra, some people call them Red Neon Tetra. 

This species is quick to replenish, ensuring there won’t be any shortages of Cardinal Tetras any time soon. Their popularity among aquarium enthusiasts ensures that you will find them in most pet stores in general for about $2. 

These fish originated in the South American Negro and Orinoco Rivers, even as far west as Columbia. Schools of Cardinal Tetras have been spotted in Manaus, northern Brazil, probably having escaped from collectors. Several species of the Tetra family have originated from South America, although some species have been found in Central America and Africa. 

The Cardinal Tetra makes a great beginner fish. Easily incorporated into a community tank, they can withstand a range of conditions due to their hardy constitutions. Take care of these fish properly, and they will live up to at least five years.


People are attracted to the Cardinal Tetra because of their vibrant coloring. They don’t get big, growing to be about 2-inches long. Their fins are small and indistinct, not showy at all. 

Their body is an electric blue with a bold red stripe that runs from the head to the tail, underneath the blue. The red from the stripe bleeds into the tail fin, which is transparent, as all the other fins are. Its underbelly is an off white that sets off the other electric colors beautifully.

A shoal of Cardinal Tetras is a strikingly hypnotic sight. Adult Cardinals living in soft and acidic waters will show their colors more vibrantly. You can also find Tetras in silver and gold, although they aren’t as common as the Neon and Cardinals are. 

Because they have the same color patterns, it’s almost impossible to identify the females from the males. When the females are carrying eggs, their bodies become rounder, making them easier to distinguish from the males. 

Cardinal Tetra vs Neon Tetra

Because of the similar coloring, the Cardinal Tetra is often confused for the Neon Tetras. However, the Neon Tetra’s blue stripe is not as vibrant a blue as the Cardinal’s. Plus, the Cardinal’s red streak runs from their tail to their head, whereas the Neon’s red stripe only goes halfway across their body. Both of these differences make the Cardinal Tetra brighter, more brilliant in coloring than the Neon Tetra. 

Habitat and Tank Requirements

The Cardinal Tetra’s natural habitat is in the rainforest, where trees and foliage are very dense, covering the waterways, letting little light through to the water. They love the shaded areas that have clear, standing pools of water, or slow-moving water that has very soft and acidic water, usually with the pH being around 5. 

They naturally live in large schools, even in groups as large as one or two hundred. They prefer the middle water column, where they can feed on small crustaceans and worms. 

Similar to the Neon Tetra, the Cardinal Tetra prefers a mature tank with soft and acidic water. The water chemistry in the tank must remain stable. Cardinal Tetras do not do well in newly started tanks. 

For the tank, you want to keep the pH level below 6, while the hardness level needs to be 4dGH and below. This species does not do well in water with high mineral content. It will cause them to be unhealthy and ultimately lead to shortened lifespans. The temperature of the water can vary between 73° to 81°F (23°-27°C).

The lighting and decor in your tank should be rather subdued. Floating plants are perfect for moderating the tank’s lighting. The Cardinal Tetras need open space to swim around in, but they also need some hiding spots, as well. Planting your tank along the edges but leaving the center open is an excellent habitat choice for your Cardinals.

Cardinal Tetra Tank Mates

As we mentioned earlier, Cardinal Tetras are a schooling fish. They are social and active, but peaceful, as well. When buying Cardinals, you should buy a school with at least six of them, but the bigger, the better. 

They acclimate well to community tanks, just make sure that the water conditions are agreeable and the other tank occupants are peaceful. Other species of Tetras make excellent tankmates, as do Dwarf Gouramis, Rasboras, Danios, Mollies, Hatchetfish, Guppies, Angelfish, and the smaller catfish members

Otocinclus and Loaches, such as the Zebra Loach and the Yoyo Loach, are a great addition to your tank if you are looking for fish that occupy the bottom areas of your tank.

If you want to diversify your tank further, you can add Mystery Snails and Cherry Shrimp, which are both compatible with your Cardinals.

The bigger catfish tend to eat anything that will fit in their mouths, so it’s best to keep to the smallest members of that particular species family. The same goes for any other fish that is big enough to eat a two-inch Cardinal Tetra.

Your Cardinal Tetras tend to stay within their own schools, ignoring the other tank occupants. You do want to avoid aggressive and territorial fish species that might bully or pick on your Cardinal. If they are treated this way, they can become so stressed out that they will die.

Keeping Cardinal Tetra Together

Cardinal Tetras do not do well alone or in small groups. Instead, they do best in larger shoals of at least six other Cardinals. This will keep them happy and healthy, as well as allowing them to be themselves and act natural. The bigger the shoal of Tetras, the happier they will be.

Food and Feeding

Cardinal Tetras are omnivores and will eat most foods you give them. However, they do require a lot of vitamins, so their diet needs to be at least three-fourths flake food, higher quality is best.

They like to eat frozen and live foods, but if you only feed them those, they may become picky and reject anything else you try to feed them later, preferring only frozen or live foods.

If you are only feeding them once or twice a day, make sure that they eat everything within five minutes. Although, it’s better to feed Cardinals several times in a day, giving them only the amount they can eat in a three-minute time frame. If anything is left over, remove it from the tank to keep it from breaking down in the water.

Green vegetables added to their diet will not only diversify their diet but give them the added nutrients they need. Because the Cardinal Tetras have a smaller mouth, you will need to make sure that everything you feed them is in small pieces.

Cardinal Tetra Care

The Cardinal Tetra makes a great starter fish because of how easy they are to take care of. They can easily tolerate a wide variety of setups and water conditions

Their diet plays an essential part in their health. If their diets are not rich in the nutrients their little bodies need, their immune systems will begin to weaken, and they will start to lose color, become duller, less vibrant.

Sudden changes in their environmental conditions can weaken their immune systems, as well. If there is a drastic change in temperature, the health of your Cardinal Tetras will be severely compromised, and they may not survive for long.

Along with the tank parameters remaining stable, you should always make sure your aquarium is kept clean. To prevent the buildup of harmful pollutants, you should change the water regularly, as well as wiping down any excess algae that have formed before it can become an issue.

Many of the Tetra species are affected by the Neon Tetra disease, and the Cardinal Tetra is no different. This particular disease is caused by a nasty parasite that causes secondary infections, curved spine, cysts, color changes, and loss of color.

This parasite can infect your tank when you add fish that have not been quarantined to your tank. It can also infect live foods that you feed your fish, thereby contaminating your fish. 

Unfortunately, there isn’t a cure for this disease, and your fish will die if infected. If you suspect your fish of being infected, remove them from the tank as soon as possible. This way, they will not contaminate the remaining fish in your tank.

Other diseases that could affect your fish include bloat, ich, and fin rot. However, these diseases are well-known and easy to treat if caught in time. 

How to Breed Cardinal Tetras

In their natural habitat, the Cardinal Tetra will breed in shaded regions, upstream. With the proper conditions mimicking their natural habitat breeding environment, you can breed them as home. 

You will need a separate breeding tank, with no lighting. A clean tank is essential, so you will need to clean and change the water every week. You can’t allow algae or pollutants to build up in your breeding tank. 

It’s necessary to keep the water chemistry stable to ensure the health and breedability of your Cardinals. The pH should be between 5.0 and 6.0. The water needs to be very soft, no higher than 5 dGH, preferably around 3 dGH.

A healthy, nutrition-rich diet is essential for preparing your fish to mate. A diet of live foods and frozen foods are best and will deliver the needed nutrients to your fish. 

The female’s body will become rounder when she’s carrying eggs. She will also allow the male Cardinal to swim around the plants alongside her as she releases the eggs, while the male fertilizes the eggs.

They usually spawn in the evening time, sometimes continuing late into the night. They will spawn anywhere from 130 eggs to 500 eggs. Once the eggs have been spawned and fertilized, you will need to remove the adult Cardinals from the breeding tank.

The eggs will hatch within three days, living off the yolk sac for about four to five days. Because the fry will be too small to eat a regular adult diet, you should start feeding them infusoria once they start free-swimming. You can also feed them egg yolks, rotifers, and commercially prepared fry foods. You can begin feeding them brine shrimp that has been freshly hatched once the fry begin to grow. 

The fry will tend to be a bit photo-sensitive once they have hatched, so you will need to raise the light intensity gradually up to regular conditions. Floating plants are a great way to limit the light being filtered into the breeding tank. 

The fry’s colors will match the adult’s coloring in about 8 to 12 weeks. Once matured, they will be about 2-inches long in your home aquarium.

Are Cardinal Tetra Suitable For Your Aquarium? (Summary)

The Cardinal Tetra makes a delightful addition to anyone’s tank, whether they are a beginner or a seasoned aquarist. You are guaranteed to enjoy watching your Cardinal Tetras schooling together and darting around your tank. With their electric red and blue coloring, the sight can be calming and hypnotizing. 

Whether you choose a species-specific tank or a community tank, these fish are hardy and fun to keep. They are peaceful enough to make great tankmates with your other fish. Just remember to keep the safety of your Cardinal Tetras in mind when choosing their tankmates. You don’t want to expose them to fish that may bully, pick on, or even eat them. 

If kept properly, your fish will live a long and happy life, and you will reap the benefits of a beautiful aquarium full of vibrant fish that are a joy to watch.

Do you keep your Cardinal Tetras in a community tank? Let us know about your setup in the comments section below…

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Michele Taylor
Michele Taylor

Hello, fellow aquarists! My name is Michele Taylor, and I am a homeschool mother of six children, which includes five boys and one girl. My kids range in age from five-years-old to eighteen-years-old.

Growing up, our family had a large aquarium with angelfish, goldfish, and lots of different varieties of neons. We also had a “suckerfish” that grew to be about six inches long.

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