Cardinal Tetra Care Guide – Size, Lifespan & More

The cardinal tetra is a beautiful freshwater fish popular among aquarium enthusiasts. Click here to learn how to care for these great fish.

Cardinal Tetra – Quick Facts

In a rush? Check out the quick facts about Cardinal Tetra below.

Fish Info

Scientific NameParacheirodon axelrodi
Common Namescardinal tetra
AppearanceThe cardinal tetra has 3 main colors: one neon blue stripe running from the head to before the tail; one red stripe below the blue, running from just behind the head until the tail; and a white underbelly.
DifficultyCardinal tetras are more difficult to care for than other tetra species because they are more sensitive to water fluctuations.
DistributionThe cardinal tetra is found on the upper Orinoco and the Negro rivers, which are located in Colombia and Venezuela, and Brazil, respectively.
LifespanThe typical Cardinal Tetra lifespan is between four and five years when healthy.
TemperamentThe cardinal tetra is a peaceful and mild creature that becomes fearful and shy in small groups
Keep in Groups of6 or more.
Tank MatesRasboras, Danios, Guppies, Mollies, Loaches, Hatchet Fish, Swordtails, Dwarf Gourami, Platies, Common Plecostomus, Corydoras
DietThe diet of cardinal tetra should consist of three-quarters dry flakes or pellets, with the remaining quarter consisting of worms or small crustaceans.
Length1-2 inches
Sexual DimorphismThere is very little sexual dimorphism among cardinal tetras, with the main difference being size. Females are usually slightly larger than males.
Breeding DifficultyCardinal tetras are not easy to breed as they require certain water parameters, among other things.

Water/Tank Recommendations

Water TypeFreshwater
Water TemperatureThe ideal water temperature for cardinal tetra is 23-27°C (73-81)°F.
Water pHThe ideal water pH for cardinal tetra is 5.5-7.5.
Water HardnessThe ideal water hardness for cardinal tetras is between 5-12 dH.
Tank sizeThe minimum tank size for cardinal tetra is 20 gallons. The recommended tank size is 30 gallons.


The Cardinal Tetra is a beautiful little freshwater fish that many aquarists have grown to love. With their interesting appearance and approachable temperament, it’s no wonder why!

While they can be easy to care for, below are a few things you ought to be aware of if you want them to live long, happy lives. This guide will go through all the essential info about Cardinal Tetra care so you can provide them with the best habitat possible.

About Cardinal Tetra

The cardinal tetra is a beautiful freshwater fish that can be found in most pet stores around the world. It’s not as commonly seen as some other species, but it is still very common in its own right!

These fish are peaceful and easy to take care of. They do very well with a wide range of tank mates and will spend their time swimming at the bottom or middle of your aquarium.

Cardinal tetras have been kept as pets for over 50 years now. They get their name from their distinct red coloration, which resembles Catholic robes worn by cardinals during masses.


The first thing you’ll notice about the Cardinal Tetra is its vibrant colors. One of the first things you will notice is the blue stripe that runs from head to tail. The rest of the body of this fish is a bright red color.

While some fish might have a faded or faint outline, these fish are known for having bright and intense blues on their scales, making them very noticeable in your tank.

Their Length

The average Cardinal Tetra length is about 1-2 inches. However, this can vary depending on their diet and the quality of care they receive.

This makes them one of the smaller species in the Characidae family. While some aquarists prefer larger fish that are easier to see, others find small fish like these quite charming.


The average Cardinal Tetra lifespan is between four and five years when healthy. This means that this fish species has a fairly long life span, making them an investment for any fish owner.

However, there are no guarantees when it comes to the lifespan of these freshwater fish. Many things can affect their overall health and lifespans, including water conditions, diet, and genetics.

To help your Cardinal Tetra live as long and happy a life as possible, it’s important to provide them with the best care you can.

Sexual Dimorphism

There is very little sexual dimorphism among cardinal tetras, with the main difference being size. Females are usually slightly larger than males.

Females are a bit larger, which allows them to hold more eggs. This is especially important if you plan on breeding them.


The natural habitat of the Cardinal Tetra is slow-moving streams and tributaries rich with vegetation. The waters are often stained with tea-colored organic matter, making the plants they have access to even more important.

These fish prefer dense cover and floating driftwood branches where they can take shelter when frightened or tired. They need places to hide so that they can feel safe when needed.

When it comes to the substrate, a rich dark sand is best. This will allow plants and other decor you choose to have maximum visibility without affecting water quality.

Caring for Cardinal Tetra

Cardinal tetras are very hardy fish that can adapt well to a number of conditions. However, it’s important to stick with recommended water parameters if you want them to live as long as possible.

Aside from the water requirements (which we will cover below), these fish do not need much special care. No fancy equipment or extreme tank conditions are required for this species!

Like any other tropical freshwater fish species, cardinal tetras thrive when kept in an environment that resembles their original habitat.

The bottom of the aquarium should be covered with dark sand (they prefer a sandy substrate rather than a rocky one). Add several pieces of driftwood and various plants throughout your aquarium too.


Cardinal tetras will happily eat flakes and pellets, but you need to make sure that the food is of high quality.

They also require protein-rich snacks as well (this can be worms or crustaceans). Make these protein-dense treats rare since they are rich in nutrients. Too much may result in indigestion. Please exercise caution when feeding them!

Also, make sure not to overfeed your fish. Overfeeding can lead to a variety of health problems and ultimately shorten their lifespan.

How Often & How Much to Feed Them

Cardinal tetras are very active and energetic, so they will need a lot of food to keep up with their metabolism. However, this also means you must be careful not to overfeed them!

We recommend feeding your fish once every day or two. Feeding them twice a day is too much because it can lead to algae growth in your tank due to excess nutrients being released into the water. This excess results in less oxygen for other aquatic life as well.

Also, give each fish no more than 2-3 small pinches of flake food at once. If you’re unsure how much is appropriate, observe their eating behavior and adjust accordingly.

Possible Diseases

Cardinal tetras are susceptible to common aquarium diseases, such as ich and fluke. Ich is a contagious disease that can quickly wipe out an entire community of fish in your tank if left untreated (it’s highly contagious).

To treat it, you must quarantine the infected fish and increase water temperatures up to 86 degrees Fahrenheit for a few days (but increase it slowly; roughly 2 degrees every 3 hours is best). Be sure your fish can handle this temperature. If this isn’t possible, try using medications instead.

Fluke causes white spots on your fish’s body, accompanied by redness and inflamed gills. Though not as dangerous or fast-spreading as ich, it still requires quarantining treatments.

Tank Setup

A well-decorated aquarium is a must when it comes to keeping Cardinal Tetras healthy. These fish are naturally shy and tend to stay hidden when they feel threatened.

Providing hiding places like caves, plants, and driftwood will help these fish become more confident and active. Hiding spots also give them a place to retreat from aggressive tank mates or other stressful situations that might arise throughout their lives.

The bottom of the tank should be covered with a fine substrate like sand for adequate swimming space. The water should flow faintly and smoothly.

Aquarium Size

The ideal aquarium size for Cardinal Tetra is 20 gallons. However, we recommend going larger if possible.

These fish need plenty of open space to swim around in a multi-species community tank. When you add other similarly sized shoaling species into the mix, it’s important to provide ample swimming room and hiding places so that no one feels too crowded or threatened.

If you plan on keeping more than a dozen Cardinal Tetras together, consider getting an even larger aquarium (aim for over 30 gallons) to accommodate their social needs.

Water Conditions

One thing that is important when it comes to Cardinal Tetra care is staying consistent with the water parameters.

You must closely monitor these levels and only make slight adjustments rather than drastic ones to avoid stressing out your fish.

  • Water temperature: 77°F-82°F (aim for 80 degrees)
  • pH level: 5.5-7.5 (target 6 or neutral pH)

Make sure you have some kind of water filtration system in place because cardinal tetras are sensitive to nitrate buildup from waste products.


The pH balance of the water is extremely important for all fish. For Cardinal Tetras, maintaining the proper level of acidity in the tank is crucial to their health and well-being.

The recommended pH range for this species is between 5.5 and 7.5, which should be relatively easy to achieve with regular testing. Anything outside that range could lead to serious health issues like stress or disease.

Investing in an accurate testing kit for your tank is a good idea. A test should be conducted about once a week to ensure that the water is within acceptable levels.


The best water temperatures for Cardinal Tetras are between 72 and 82 degrees Fahrenheit. This is on the higher end of the temperature spectrum for some fish, so keep an eye on this to avoid any accidents caused by heat fluctuations.

If your aquarium heater malfunctions or isn’t big enough to handle the tank size, there could be instances where these fish suffer as a result.

Look into a tank heater that’s big enough to handle the aquarium size, and make sure it’s up to snuff, so you don’t have any issues.


This is possibly one of the most commonly misunderstood aspects of fish care, so we’re going to get super nerdy on you.

Hardness levels measure the amount of dissolved minerals in your water (primarily calcium). Since many tropical fish come from soft waters, it’s important to have adequate hardness if they are going to live in a tank.

Minerals like magnesium and sodium can be dangerous for some species. In our opinion, this is an area that new aquarists don’t spend enough time researching when setting up their first tank. This could potentially lead to disastrous consequences down the line!

Fortunately, getting perfect hardiness levels isn’t as difficult as you might think. You need a test kit and make adjustments based on its readings!


When it comes to filtration, you need to take special care when setting up the tank. The cardinal tetra is sensitive to ammonia and nitrites that build up in the water over time.

To combat this, choose a high-quality filter with strong protein skimmers. They should also be able to cycle through enough water daily so that waste doesn’t accumulate.

Note: Make sure that you’re cleaning the filter regularly to avoid ammonia from getting out of hand. A weekly cleanse should be enough.

Aquarium Plants

Planting the right plant life in your Cardinal Tetra aquarium is essential to provide them with a happy and healthy environment. There are many different kinds of both real and fake plants that can serve as tank decorations.

When choosing tank plants for Cardinal Tetras or any other fish in your community, there are three main things you need to consider: size, growth rate, and pH balance.

Before adding a plant to your aquarium, make sure that these 3 aspects are suitable for your tank. The plant needs to not be too big, and it must be compatible with the pH of the water.

Behavior and Compatibility

Cardinal tetras are very social fish that enjoy the company of others. When kept in groups, they display some unique behaviors.

For starters, they like to swim together in a shoaling group. This means you can expect to see many Cardinal Tetra swimming around the tank simultaneously!

These fish also exhibit schooling behavior when threatened by larger creatures or simply when trying to navigate difficult waters. They will move as a unit and take turns darting ahead before swarming behind each other again.

How Many to Keep Together

It’s recommended to keep six or more together. This is because they are shoaling fish that need the social support of others in order to feel safe and confident. When left alone, a single specimen will become timid, shy, and scared.


The Cardinal Tetra is a peaceful species that does not want to cause trouble. They are very shy when placed with larger or more aggressive fish and often spend time hiding until they feel comfortable enough to venture out.

This is why it’s paramount that you keep them in a group of 6 or more. Hiding in large groups can help the little fish shed its shyness and become much livelier! When grouped together, these tiny creatures tend to zip through the water together as one. It’s quite beautiful to watch.

Note: There have been reports of Cardinal Tetras being prone to aggression if kept with other similarly-sized species, such as Neon Tetras or even smaller types of Cory catfish. These instances are rare but something you should be aware of.

Tank Mates

The best tank mates for Cardinal Tetras are any other type of tetra.

You can also keep them with pretty much any docile fish species that share the same water conditions. Here are some suitable tank mates:

  • Rainbow Shark – These fish have a similar body shape and swim in a similar fashion. They bear a small resemblance to sharks, which can add some excitement to your tank. They are both very active, too, making them great tank mates because there is always something going on when sharing space.
  • Harlequin Rasbora – This colorful freshwater species will quickly become friends with your Cardinal Tetra because of its bright colors. You may even see them swimming together if you pair enough of each kind together!


Breeding Cardinal Tetras is not hard if you have the right tank and water conditions. However, these fish are egg-layers that need specific parameters to breed successfully.

The first thing to do is separate your breeding pair into a tank by themselves. Ideally you want soft, acidic water in this tank that is around 80-84 degrees Fahrenheit.

When they feel ready, female Cardinal Tetras will lay their eggs for the male to fertilize. To encourage this behavior, provide plenty of hiding spots for her to choose from (we recommend utilizing moss). After fertilization has occurred, remove both the male and female from their own tanks so that they don’t eat their newly laid eggs.

Eggs can hatch within two days after being laid, so check on them frequently until this happens.

Are Cardinal Tetra Fish a Good Choice For Your Tank?

Cardinal tetras are a beautiful freshwater fish that we recommend to new aquarists. In fact, they’re one of our favorites!

However, there is an element of difficulty in their care requirements that you should be aware of before getting some for your tank. These fish can have sensitive water parameters and diet needs, which makes them trickier than other common species like the neon tetra or Oscar cichlid.

If you think you can provide good care for this species, then by all means, go ahead! We know plenty of people who own cardinal tetras and love them.


One of the best aspects of owning a cardinal tetra is its beauty. This species has an incredibly vibrant look that’s easy on the eyes.

They also have a fun shoaling behavior and will swim together constantly! Watching this group swim around your tank can be quite mesmerizing. It’s like watching a tiny school of fish!

Another great quality of these beauties is their hardiness. Cardinal tetras are pretty low-maintenance, especially compared to other tropical freshwater fish.


The cardinal tetra is a beautiful fish that’s easy to care for. However, they have some disadvantages you should know about before getting them.

We prefer sticking to established guidelines rather than taking advice from random sources online.


Cardinal Tetras are an interesting and fun freshwater fish to have in your aquarium. They’re gorgeous, easy to care for, and very active.

If you have some experience with the basics of fishkeeping, then we highly recommend this species. You won’t be disappointed!

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