Hot Water Fish

Cardinal Fish, Cardinal Tetra


  • Scientific name: Paracheirodon axelrodi
  • Common Name: Cardinal Fish, Cardinal Tetra
  • Aquarium size: 60 liters
  • Temperament: Pacific
  • Temperature: 23ºC to 27ºC
  • pH: 4.6 to 7
  • Diet: Omnivore
  • Length: 5 cms.


The Cardinal Fish or Cardinal Tetra is a species of fish that belongs to the Characins family , so it is related to piranhas , although it does not have much of its aggressiveness, and it is also related to the Neon Tetra.

This species was discovered and described by Myers and Weitzman in 1956.
Despite the time that has passed since then, it
is still one of the most spectacular freshwater fish species we can breed.

They are fish of a lively temperament, active swimmers, who like enough spaces to move.
A fun and safe bet for any aquarium.


The Cardinal Fish is relatively small, in the aquarium it does not reach more than five centimeters in its adult stage.

They have a slender and tapered body, with large eyes that cover much of the space dedicated to the head.

Its fins are transparent, while its body is reddish in color , similar to the Neon Tetra (with which it is related), but with a more intense and bright red color, which extends through the ventral part of the fish.

Currently you can already find
Cardinal Tetras in gold, platinum and albino colors.

Longitudinally a bright bluish-green stripe is crossed, and under this stripe we appreciate the bright red color of the fish, which extends from the tail to the head.

It is not easy to distinguish between males and females, except when they are adults. Female Cardinalfish are slightly rounder and larger than males.

Distribution and habitat

Their origin is in Brazil , they can be found in the Negro river basin and its tributaries.

It is possible to find Tetra Cardenal also in the Orinoco River, Venezuela, although with slight morphological differences.

They develop their life in
forest streams, with relatively slow water currents,  abundant vegetation and substrates covered with fallen branches, roots and litter.
They are acidic waters and usually stained brown , thanks to the presence of a large amount of decomposing plant matter.

Aquarium conditions

They need an aquarium of between 50 and 60 liters , where we will find them swimming in the intermediate zone.

the aquarium should be densely planted . They like thin-leaved plants, which provide safe shelter, especially during the breeding season.

They don’t like intense lighting.

The water must have the following characteristics:

  • Temperature between 23ºC and 27ºC
  • pH between 4.6 and 7
  • gH 3 to 6 degrees


They are fish with voracious appetites, which will accept all kinds of small foods. In the wild they will eat all kinds of small invertebrates, crustaceans, algae and fallen fruits from trees.

In the aquarium we can try to imitate this diet by providing
live food based on brine shrimp , mosquito larvae, daphnia, although it will also accept any type of dry food for tropical fish .

Behavior and compatibility

Although they are very active swimmers, they are peaceful fish if they are kept within a small school , which should have between 8 and 10 individuals.

To avoid the temptation that it can attack other fish, ideally
we will look for companions of similar size among the different species of characins.

It is also usually kept on the sidelines with
corydoras and medium-sized cichlids .


Its reproduction in a home community aquarium is quite difficult , although not impossible.

If you want to try to reproduce Cardinal Tetra in your aquarium, you must follow the following instructions:

  • The aquarium should be dimly lit, with an abundance of thin-leaved vegetation, such as Java Moss . Cardinal fish usually lay their eggs on their leaves.
  • A good idea is to cover the bottom of the aquarium with a mesh , which prevents the adults from eating the eggs.
  • Water conditions: pH between 5.5 and 6.5, with a gH between 1º and 5º. The temperature must be kept between 16ºC and 22ºC.
  • To promote spawning you should have a group of about six specimens of each sex.
  • You have to increase the amount of protein they eat, you have to give them lots of live foods.
  • They often lay their eggs in the middle of the night , when the lighting is lower.
  • When the spawning has finished and the males have fertilized the eggs, it is convenient to remove the adult specimens to another aquarium.
  • Hatching occurs after 36 hours , and we will have fry swimming freely in 3 or 4 days. They don’t like light, so lighting has to be very dim for the first few days.

Photos of the Cardinal Fish

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