Cardinal Tetra – A Complete Guide (Care, Diet, Facts)

Tetras are one of the more recognizable aquarium fish out there.  They have become popular because of their vibrant colors and being easy to care for.  The most popular tetra being the Neon Tetra.

The Neon Tetra is not the most vibrant in color though.  The Cardinal Tetra is twice as colorful and as easy to care for.  This school fish will dazzle your tank as the group speeds by in a flash of blue and red.

Cardinal Tetras have gained popularity in recent years.  Breeders are now having more success in producing this species.  They are difficult to breed in captivity.

Whether you are new to fish keeping, or have been at it for years, the Cardinal Tetra is a perfect fit for you.


The Cardinal Tetra at a Glance

The Cardinal Tetra (Paracheirodon axelrodi) are a freshwater fish native to South America.  They live in the Orinoco River in Venezuela and the Negro River in Brazil.

In the wild, you can often find them swimming in groups of hundreds of tetras called shoals.  Tetras prefer being in standing or very slow moving river water.

Their increasing popularity makes them easy to find in shops for a low price.  Most tetras you find in shops will be from the wild and transported.  Wild tetras are able to transition well into the right sized tank.

You can find tetras bred in captivity instead of caught wild.  Some prefer this due to the ethics involved.  Tetras fins are often damaged by nets when caught wild.  Inspecting them can give you an idea of where they’re from.

They are quite a small fish, growing to be two inches long at most.  With a group of them, they will make a big tank seem full.

Cardinal Tetra are mild in nature and easy to care for.  This makes them great for beginners and experts alike.

These fish are a great option for adding some color to the tank.  Their bright red and blue stripes and white under body make for beautiful tanks as they swim around.

Their vivid colored body will show up best in very soft and acidic water.   Although rare, it is possible to find the Cardinal Tetra with gold and silver colors instead of red and blue.

Cardinal Tetras are peaceful fish which is good in a community tank.  They are also okay with being by themselves too, good for those who want to stick to one species at a time.

They are a strong fish who can live up to five years.  They don’t need much besides a clean tank and good diet.

Cardinal Tetra Care

Part of the reason Cardinal Tetras are a good beginner fish is because they are easy to care for.  Here are a few tips to make sure your tetras have a happy environment.

Maintain your water quality.  Plan to replace 25% of your tank’s water each month.  If the water begins to look murky, or cloudy areas appear on the glass, this could be a sign of algae buildup.

Investing in an algae scrub brush will make cleaning the tank easier.   After scrubbing, rinse well with running water, making sure to get all the debris out.

Keep your water temperature stable, any sudden drops or spikes could cause your tetras to die.  An in tank thermometer makes this check quick and easy.

Tetras losing color means something is wrong.  Common causes are poor diet, water conditions, and too much lighting.  It is important to find the cause right away to prevent them from getting worse.

Antibiotic placed in the water will treat sick fish.  Antibiotics can help with fin rot, fungus, gill disease, and more.

A more serious cause of losing color is Neon Tetra Disease.  Though named after the Neon Tetra, Cardinal Tetra are still susceptible.  It can enter your tank through new fish or contaminated live food.

If you suspect it is because of a new fish, call the shop where you got it from. They might offer a refund and they can take steps to protect their other fish.

Most likely, you will not know your fish has Neon Tetra Disease until symptoms start showing. Symptoms include: loss of color, curved spine, and cysts.

If you notice any of these it would be wise to remove the fish in question to prevent it from spreading.  There isn’t a cure for Neon Tetra Disease yet, most fish with the illness will die.

Feeding and Diet

Cardinal Tetras are omnivores by nature. In their wild South American habitat, they will eat larvae, eggs and worms.  When bringing a tetra home, dried flake food is fine, as long as it is of high quality.

High quality fish flakes will list fresh seafood at the top of its list of ingredients.  Low quality fish flakes will use a fish meal as their main ingredient.  Fish meal contains fish parts that lack nutrition and are indigestible.

When browsing flake food make sure it is for small mouthed fish.  High quality fish flakes are available at pet shops or online.  Flakes do not keep very long and lose nutritional value once opened, so don’t buy in bulk.

Although tetras will eat dried flake food, it is best to include small portions of live or frozen food as well.  Due to the tetras small mouths, most available live foods are too big for them to consume.

Adult brine shrimp and daphnia (water fleas) are the appropriate sized live food.  You can buy these online or in stores.  Mosquito larvae is another good option, but may be illegal in your area to cultivate.

The feeding routine should take place twice a day.  Once in the morning and once in the evening.  Feed them only what they are able to eat in a 2-3 minute window.

Until you figure out the right amount of food, remove any excess from the tank after the feeding window.  Doing this will help to keep the tank clean and prevent overeating.

Tank Conditions

Cardinal Tetras live in the wet forest areas of South America such as rivers, streams, and ponds.  Even with the plants and rocks in the water there is still plenty of open water for them to swim.

Your Cardinal Tetras want some plants in their tank to hide in when needed, but open space is key to keep them happy.  They will stay in the middle to top area of the tank.

When considering what to add to the bottom, sand is a good option.  Sand is a more natural option then colored gravel.

Sand keeps debris on top making it easy for the flow of water to pick it up and run it through the filter.  This makes less work for you when cleaning the tank.

Make sure to keep the water temperature and pH level in check.  Keeping the temperature and pH right will help your tetras to fight illness and be healthy and happy.

Temperature should be between 73-81 degrees Fahrenheit  (22-27 degrees Celsius).  pH is the measure of the acidity or alkalinity of the water in your tank.  Your tetras will thrive when the pH of your tank is in the 6-7 range.

Cardinal Tetras like to be with groups of their own species to swim together.  When considering them for your aquarium you should have at least six of them.  More is fine as long as the tank is large enough.

A group of six tetras will need at least a 20 gallon tank.  If adding more, increase the water an extra 2 gallons per tetra and increase the tank size as needed.



Trying to breed this species at home can very difficult and frustrating.   Follow this guide if you want to give it a try.   Those looking to start fish breeding should begin with an easier fish.

You can breed Cardinal Tetras at home with some extra tanks and good conditions.  You will need to mimic the natural breeding habits for tetras.  They breed in the darkness of the South American rainforest in groups.

At home your tetras will breed in pairs, select your male and female and put them in separate tanks.  Feed them live food until the female appears rounded with eggs and the male has vivid colors.

Once they are both ready, place them in the breeding tank together.  The breeding tank should be very dark and at a temperature around 82 degrees Fahrenheit.  Keep the water very soft and acidic, with minimal nitrates.

Cycling and filtering of breeding tanks is very important, a sponge filter is a good choice.  The tank will also need live plants for the female to place her eggs in.

Java Moss is a great option as it provides good cover for the eggs.  You can buy Java Moss in most aquarium stores or online.

In the breeding tank, the male will attempt to swim alongside the female in the plants.  If the female accepts, the male will start to release his sperm as the female releases her eggs on the plants.

Remove the parents from the tank as soon as the breeding has taken place.  It is important to keep the tank in complete darkness during this time or the eggs will die.   The eggs will hatch in 2-3 days.

The newborns will be sensitive to light.  Only have minimal light in the tank for at least a week after they are born.  After a week has gone by start introducing light back into the tank in small amounts.

For feeding, use any commercial fry food or infusoria for a few weeks.  Once they have grown a bit more they can start eating crushed flake food.  Live foods like Baby Brine Shrimp and micro worms provide good nutrients too.

Breeding Cardinal Tetra is not an easy task.  Even professional breeders have had a difficult time with this fish.  Breeding is not recommended for beginners, but you are welcome to give it a try. 

Tank Mates

Due to the Cardinal Tetra’s peaceful nature, they are good for community tanks.  They will keep to themselves without disturbing others.  Cardinal Tetras are a hardy fish and have a lifespan of about 5 years with good tank conditions.

When considering tank mates, smaller ones are best for the tetras.  Bigger varieties of fish could view the tetras as food and attempt to eat them.  Big fish can also stress the tetras.

Aggressive, or territorial, fish are not good companions.  Even if they are the same size as the tetra, or smaller.  These kinds of fish can stress them to death.  One example is the Rainbow Shark.

Good tank mates include the Cardinal Tetra’s relative the Neon Tetra.  They are very similar in looks but the Neon Tetra’s red stripe only goes halfway down its body.

Small fish like Guppies, Angelfish, Dwarf Cichlids and Zebra Danios are good as well.  For more variety try snails, shrimp, or crabs, they pose little threat to the tetras.  Cherry Shrimp and Mystery Snails are the most common.

Cardinal Tetras stay in the top and middle of the tank so bottom dwellers are a good addition.  Zebra and Yoyo Loaches and Otocinclus are a great fit.

As a schooling fish, Cardinal Tetras will only school with their species.  Make sure to have at least half a dozen of the same species in the tank.  There are many different types of tetras and not all are compatible.

Always compare habitat requirements for compatibility on any new tank additions.  Keep a sharp eye on the new creatures for the first few days, looking for any signs of illness or stress.


Cardinal Tetras are a great fish for beginners.  It is easy to care for them, and it does not cost a lot to build their aquarium habitat.  They are a hardy species and peaceful around other fish.  This allows for a variety of tropical freshwater aquarium builds.

This vibrant, and active, fish will make viewing your tank an enjoyable experience.  Not only for you, but your friends as well.

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