Cardinal Tetra (Red Neon Tetra): Profile and Information

Cardinal Tetra

Cardinal tetra, debatably the most famous of small tetras, has some close similarities to the neon tetra.

Even they breeding them in captivity may be difficult, cardinal tetras are very energetic schooling fish that dwell peacefully in community aquarium.

They are still well known aquarium fish.

Overview of the Cardinal tetra

  • The cardinal tetra is also referred to as roter neon, large neon tetra, or red neon.
  • It’s scientific name is Paracheirodon axelrodi.
  • It can grow up to 5 cm (2 inches) long and it can live up to 4 years.


  • Origin: Colombia, Brazil, and Venezuela
  • Family: Characidae
  • Diet: Omnivores
  • Social: Peaceful, active and great for community tank
  • Tank level: Tank can be filled from top to mid level
  • Breeding method: Egglaying
  • Caring: Intermediate
  • Temperatures: 23 to 27 degrees C (73 to 81 degrees)
  • Hardness: Can be as high as 4 dGH
  • pH level: 4.6 to 6.2


Known to originate from South America, the cardinal tetra is found in Rio Negro, western Colombia and Orinoco. Although, cardinal tetras have been seen in other locations but they are likely fishes that escaped from breeders and collectors.

One place where a bunch of cardinal tetras have become very comfortable is in Manaus, northern Brazil. Their waterways are mostly very dense, since little or no light gets through, and are covered by the rainforests.

This is very conducive for cardinal tetras as they love to bask in the shaded areas. They can be found in large numbers in areas with still or slow moving clear waters. It isn’t uncommon to find cardinal tetras in hundreds, brilliantly clustered together forming a giant school of fish.

Their natural habitat generally comprise of soft, acidic water with a pH level of 5. They can be found living in shoals, mostly in the mid-water layers, where their main diet comprise of tiny crustaceans and worms.

Markings and colors of the cardinal tetras

The cardinal tetra has been naturally designed with a noticeable neon blue stripe coursing from the nose to their tail. Right below the blue stripe is yet another red stripe. The red stripe blends beautifully well into the tail of the cardinal tetra. The fins and the tail of the cardinal tetra are somewhat transparent.

You can distinguished a cardinal tetra from a neon tetra just by the band of red that runs through the entire length of the fish. Whereas, the neon tetras have the red band run from the middle of their body to their tail.

When provided with soft acidic water, adult cardinal tetras give off the most amazing display of colors that would leave anyone mesmerized.

Cardinal tetras tank mates

The cardinal tetras are very peaceful fishes that thrive better when kept in schools. At least half a dozen of cardinal tetras are required for a community tank.

As long as the water conditions favors them and other species, then you have yourself a healthy aquatic world to help with your mental state.

Fishes that may be suitable tank mates with the cardinal tetras would include other tetra species, dwarf gouramis, danios, rasboras, and smaller or medium members of catfish.

It is also helpful when you don’t keep your cardinal tetras with fishes that eat feed on smaller fishes. Also, if the fishes in your tank have their mouth big enough to swallow the cardinal tetra, then it is best to have them separated.

Care and habitat

For optimal care of your cardinal tetras, a mature tank filled with soft acidic water is needed to keep your fishes healthy and active. The hardness of the water shouldn’t be more than 4 dGH, and the pH level shouldn’t be below 6.

You would be shortening the lifespan of your cardinal tetra if you place them in water with a high mineral content.

The goal here is to create a stable water chemistry for the fishes. Also ensure that the water temperature of your tank shouldn’t go beyond 73° to 81° (23° to 27°C). Also noticed that the cardinal tetra is nor a species that strive well in a freshly started aquarium.

Lighting should be repressed as should the surrounding décor. You can also control the lighting by introducing floating plants. Even though cardinal tetras love to swim in open spaces, they also require hidden spots where they can easily hide and do whatever it is fishes do.

A conducive environment for your cardinal tetras guarantees a healthy and active school of fish.


The cardinal tetra can be classified as an omnivore and can eat almost any food. These fish require plenty of vitamin, so ensure that quality flake food makes up for at least 75 percent of their food.

The cardinal tetras posses small mouths, so they need their food eaten in tiny pieces. If breeders are conditioned, it’s important to give them live foods.

How to know their sexes

It is pretty easy to spot some obvious differences between sexes. Female cardinal tetras appear somewhat rounder belly with a deeper body, while the males look slender. The male cardinals also possess a hook extending from their anal fin.

Breeding the cardinal tetra

It may be a bit challenging breeding cardinal tetras in home aquaria. A breeding tank must be set aside with an environment,- as listed earlier-,to suit the fishes. The tank should be stocked with fine-leaved plants, as this would aid in scattering their eggs on the leaves.

They usually spawn in the evenings, all laying eggs between 150 to 600 eggs. Spawning may happen late in the day and sometimes, into the night.

It is imperative that the mating pair be removed from the tank because once spawning is complete, the mating pair would start feeding on the eggs. It would take approximately 24 hours for the eggs to hatch and depend on the yolk sac for nutrient for up to 4 or 5 days.

You should then feed them rotifers, infusoria, or foods that are commercially prepared. Cardinal tetra hatchlings also enjoy freshly hatched brine shrimp as they continue to grow. Be sure to use floating plants to help maintain a dark tank.

Also, it is equally best to keep the lighting on the low. A young cardinal tetra (as well as other tetras), are extremely photo-sensitive.

I’m sure you enjoyed reading this article and would like to get cardinal tetras for yourself. This are some pet fish breeds might also interest you;

  • Danios
  • Rasboras
  • And other tetras

Have you kept fishes with similar traits as the cardinal tetras? Do you think you could handle keeping cardinal tetras? Share your thoughts with us in the comments.

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