Cardinal Tetra: Ultimate Guide (Care, Breeding, Diet & More)

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Written By Matt Stevens

Hi, I'm Matt! I've been obsessed with fishkeeping for over 15 years now and created this site to share my knowledge with others.

Cardinal Tetras are peaceful freshwater fish that are perfect for adding a conspicuous hue to any aquarium. Their darting movements inside the tank give the vibes of a naturally beautiful freshwater fish that any aquarist would love to have at home.

Keep them with your Neon Tetras, and they will automatically stand out inside the tank. Or, put them in a darker environment with complimentary live plants, and they will instantly transform your aquarium.

Question is, do you have what it takes to keep a thriving Cardinal Neon Tetra population at home?

This guide is dedicated to answering the common questions around Cardinal Tetras. It will give a detailed insight into the fish’s lifespan, general appearance, tank size, water parameters, diet, behavior, tank mates, breeding, and much more.

 Species Overview

Cardinal Tetras appear in scientific contexts as Paracheirodon axelrodi, a beautiful freshwater species of the Characidae family. They were first discovered in the South American content, with a dominant presence in Brazil’s rivers Negro and Orinoco.

They are a perfect schooling fish in the wild, forming a beautiful pattern with their well-coordinated movements during exploration. Generally, these fish are an excellent addition to modern aquariums, regardless of the actual tank size.

By nature, Cardinal Tetras are fashioned to withstand tough conditions in the wild. And that’s what makes them a relatively hardy species in captivity, perfect for advanced hobbyists and beginner level aquarists alike.

ColorBlue and red
LifespanUp to 5 Years
Care LevelEasy
Behavior & TemperamentPeaceful
CompatibilityPeaceful community
Food and DietOmnivores
SizeUp to 2 Inches
Tank SetupTropical freshwater with enough swimming space
Tank Size (Minimum)20 Gallons


Typically, a Cardinal Neon Tetra is fashioned to live for 4 to 5 years in perfect health in captivity. It may surprise you that these species live longer in captivity than in the wild.

And as long as you eliminate stress, diseases, and undesirable tank mates, you can be certain to help them reach their full potential in captivity.


Cardinal Tetras are sometimes confused with the standard Neon Tetras, and it’s easy to see why. In fact, such is their striking resemblance to the Neon Tetras that it may be impossible to differentiate the two species if you are seeing them for the first time.

Both species have two beautiful red and blue stripes. But unlike Neon Tetras, cardinal varieties have slender bodies with a torpedo-like configuration.

What’s more, Cardinal Tetras have an iridescent blue stripe running vertically from the nose towards the tail. Moreover, a beautiful thick band of vibrant red coloration complements the general body appearance, linking to the transparent tailfin in the process.

Such a stripe separates Cardinal Tetras from the standard Neon Tetras. While the red hue will be uniquely positioned to cover just half of the Neon Tetras’ bodies, it extends to the entire body in the Cardinal varieties.

That aside, Cardinal Tetras have characteristically white bellies with transparent fins. The females have a perfectly rounded shape compared to the slender males with distinct anal fins.


So, how big do Cardinal Neon Tetras get? Typically, a full-grown Red Neon Tetra will only measure about 2 inches in the aquarium. So, they are justly categorized as small freshwater fish.

With such a size, these Tetras can thrive in a zoned territory as the only species or with similar-sized fish. In addition, their small sizes make them easily manageable in captivity if you need a low-maintenance species to kick start your fish-keeping adventure.

Cardinal Tetra Care

In terms of quality care, Cardinal Tetras prefer a stable environment with all the right conditions for keeping a healthy freshwater fish.

Despite their manageable care requirements, it’s important to acquire background knowledge in keeping other freshwater fish before turning to Cardinal Tetras.

Fortunately, we will be covering every care aspect in detail in the forthcoming paragraphs;

Tank Size

With just a 2-inch body length in adulthood, Cardinal Tetras would certainly thrive in a small tank of 10-gallon capacity. But like we already mentioned, these fish enjoy each other’s company and would do well in small groups of up to 6 species in the same territory.

We have no problem with aquarists keeping Red Neon Tetras in 10-gallon tanks if it’s just a single species. But that would be a great concern if it’s a small group of the same fish or multiple species in the same habitat.

The general rule for keeping most freshwater fish is that the more the number, the larger the tank, and the greater the comfort. So, for a start, we recommend a minimum size of 20 gallons if you have more than one fish at home.

Water Parameters

The most vital aspect of quality care for Cardinal Tetras is the tank water conditions. Remember, you will be introducing them to an entirely new environment at home, unlike what they are used to in South America.

Cardinal Tetras thrive in warm, clean, slow-flowing waters with plenty of compact vegetation as part of the natural environment in the wild.

So, you can’t expect them to thrive in a new environment if you don’t monitor the tank water conditions regularly.

For the best results, you can cycle at least 25 to 50% of the total tank water per week while maintaining every other parameter within the standard levels;

  • Water Temperature: 73°F-81°F
  • Water Hardness: 2-6 KH
  • pH Levels: 5.0-7.5

What to Put in Their Tank?

For the ideal tank setup, Red Neon Tetras love a natural-looking environment that mimics the actual living conditions they are accustomed to in the wild. They are fond of shallow, slow-flowing rivers with plenty of vegetation in South America.

In captivity, they will want to spend most of their days towards the middle of the tank. That means fine sand would be the most suitable substrate. Fine sand not only guarantees comfort inside the tank but also recreates the actual environment in the wild.

Regarding the plant choice, Cardinal Tetras prefer a combination of submerged and floating types. And that means the Amazon Swords, Anubias, and Java Fern are all great options for the plant choice.

Even though Cardinal Tetras will want a compact aquarium with enough vegetation, they appreciate enough swimming space right in the middle of the tank. And you should keep that in mind when decorating the new tank.

In addition to the sandy substrate, you can add driftwood and rocks to the bottom of the tank to complete the natural look.

Because of Cardinal Tetras’ deep affection for the murky environments in South America, be sure to control the lighting levels inside the tank. They prefer dimmer conditions and will live their best life if everything is maintained that way. 

Common Diseases

Neon Tetra disease is a common name you will hear in the freshwater fish community, especially amongst the Tetra species. It is a parasitic infection with a worse prognosis, irrespective of when you first detect it.

Usually, infected fish food or diseased tank mates are to blame for disease spread inside the tank. The diseased species will develop spinal problems, cysts, and other potentially lethal health issues.

As heartbreaking as it may be, there’s no known cure to Neon Tetra disease up to date.

Ich is another condition you should be wary of when keeping Red Neon Tetras at home. It is a parasitic infection presenting with characteristic white spots all over the fish’s body.

Ich is often linked to compromised tank water conditions and can have a lethal outcome if you don’t act in time. However, you will find suitable medications to save your fish from its devastating effects in many cases.

On the other hand, dropsy will be more of a symptom instead of an actual infection. Its diagnosis focuses on swollen bellies, indicating fluid accumulation inside the fish’s small bodies. Be sure to seek an expert’s advice if you are unsure how to control the disease progression.

Finally, the fin rot disease affects the fish’s glowing fins and may sometimes cause them to flake and fall off without proper intervention.

Most of the diseases affecting Cardinal Tetras are aggravated by reduced water quality and poor diet. So, it’s easier to prevent them if you maintain ideal water conditions inside the tank.

Frequent water testing can help you analyze its status and make crucial adjustments that could save your fish’s life in the long run.

What Do Cardinal Tetras Eat?

Like any other Tetra species, Cardinal Tetras are natural omnivores and eat small crustaceans and worms in their natural habitat. However, they are not picky in captivity and will happily eat anything you can provide as long as it meets their dietary needs.

In general, these fish have a penchant for eating high-quality pellets and dried flakes as the primary diet in captivity. But to provide the basic nutrients, you can supplement such a diet with live and frozen foods like bloodworms, brine shrimp, and daphnia.

Rather than risking overfeeding in your Red Neon Tetra species by providing large amounts of food at once, you’d better stick to a definite meal plan accounting for multiple small meals throughout the day.

While doing so, be sure to provide small-sized foods that can easily fit the fish’s small mouths. Ideally, the Cardinal Tetras should spend a maximum of 2 or 3 minutes to complete one meal. If it’s more than that, perhaps it’s time to reconsider the feeding routine.

Behavior & Temperament

Cardinal Tetras are the ultimate peace-loving species, known for their healthy coexistence with similar species in the same aquarium. They will never show any signs of aggression if you keep them together with the right tank mates in captivity.

However, they are even more fun to watch in small groups of up to 6 species in captivity. If isolated, Cardinal Tetras will automatically become lonely and anxious and may even die from chronic stress.

Cardinal Tetra Tank Mates

Cardinal Tetras are peaceful species in a community tank with similar species. Therefore, when introducing newcomers to the same aquarium, you will have plenty of options as long as you avoid large, aggressive fish.

As usual, the more aggressive species such as the Cichlids will want to bully the delicate Cardinal Tetras, negatively impacting their health and comfort in captivity.

Sometimes, it’s unreasonable to introduce larger species to a Cardinal Tetra’s habitat even when they look like a perfect match.

Below are some of the best species that will live peacefully with the Cardinal Tetras in the same aquarium;


Cardinal Tetra breeding has been a taxing activity to many aquarists ever since these fish were first introduced to the pet-keeping community. First, you have to induce the best spawning conditions for the fish to even start thinking about breeding. There’s no shortcut to that.

You should design a fitting tank with the right breeding elements and stable water conditions for a start. Also, mature fish prefer low lighting conditions during breeding and plenty of protein-rich foods.

If you successfully pair the adult fish for breeding, the female species will lay as many as 500 eggs on the tank surfaces and other breeding elements.

Parental love is unheard of in the Cardinal Tetra community. So, you must take the adult fish out of the tank after laying the eggs.

If all the conditions are right, the eggs will hatch in as little as 24 hours, with the new fry readily accepting egg sacs within the first few days of their development.

Later, you can introduce them to baby brine shrimp, powdered food, and infusoria as they slowly learn to fend for themselves.

Don’t be surprised to see a more faded coloration in the juvenile fish. It will stay that way for some time, with the beautiful blue coloration in adulthood starting to appear after a few months.

Final Thoughts

So, are you prepared to introduce beautiful Cardinal Tetras to your aquarium? Caring for these fish is never challenging if you understand all the basics from the start.

We are constantly tempted to recommend these species to advanced-level aquarists looking to brighten their aquariums with naturally beautiful freshwater fish.

But that shouldn’t stop beginner hobbyists from enjoying the beauty of Cardinal Tetras if they have everything it takes to keep a healthy community. Perhaps it’s time to give it a try, then!