The cardinal tetra was first described in 1956 by Schultz as Paracheirodon axelrodi. This species has a few synonyms: Cheirodon axelrodi and Hyphessobrycon cardinalis.
The name Paracheirodon can be broken into two parts: “Para” means almost or unreal and implies something like looks like. “Cheirodon” means pointed pole and is a reference to the pointed teeth of this genus. The species name “Axelrodi” is a reference to the author Herbert R. Axelrod.
You may also want to know how to care for an axolotl.
The difference between males and females is very difficult to tell in the Cardinal Tetra. They both have a fluorescent blue horizontal stripe that runs from their mouth to their tail. Below this blue stripe runs a bright red band. The fins are colorless and the back and belly are silver in color. The males remain slightly smaller than the females and the females have a slightly rounder belly than the males. They are very similar to their cousin the Paracheirodon innesi or Neon Tetra.
Because of its gentle nature and behavior and its beautiful colors, it can be well combined in the community aquarium. However, a combination with bigger fish is not recommended, bigger fish are hunters and see the Cardinal Tetra as a tasty snack for in between.
The life expectancy of a Cardinal Tetra in the wild is about 1 year. In the aquarium, they can reach an age of up to 5 or even 10 years.
The Paracheirodon axelrodi has a very wide range in Venezuela, Colombia and Brazil (Rio Negro, Rio Orinoco, Rio Vaupes Rio Aturia and its tributaries). They usually occur in small shaded clear water or blackwater streams. They inhabit the middle part of the water there in usually large schools.
In the wild, the Cardinal Tetra eats mostly meaty foods. These include small invertebrates, eggs, small insects such as ants, mites and larvae, and small young fish. Anything that moves is actually eaten. In addition, they also ingest small amounts of algae.
In the aquarium, it is therefore important to give the Paracheirodon axelrodi varied food. With a varied diet of flake food but small live or frozen food such as Daphnia (water fleas) and for example freshly hatched Artemia. You can also feed them fish flakes.
The Cardinal Tetra or Paracheirodon axelrodi is undoubtedly the species most commonly kept in community aquariums. In the aquarium it does best with dimmed light or floating plants and sufficient shelter. They are shoaling fish and you should put at least 8 fish together. The larger the group the more beautiful the behavior becomes! They mainly form a shoal when threatened, a somewhat larger peace-loving species like the swordtail ensures that they are not eaten but will form a shoal faster.
The water temperature can be between 23 and 29 degrees. However, make sure not to keep the fish at the minimum or maximum temperature all year round. This can actually shorten the life span of the fish.
Susceptibility to Diseases
It is a species that is very susceptible to white spot and changes in water composition though, often being the first fish to get this disease when something goes wrong with the water quality. When moving this species be sure to use the drip method to get them used to the new water composition.
Breeding the Paracheirodon axelrodi – Cardinal Tetra
Breeding cardinal tetras is very difficult. There are only reports of occasional successful breeding.
Use a breeding aquarium with very soft water with a pH of 5.5 to 6.0. Furnish the aquarium with Java moss or a laying grid and low lighting. The eggs will hatch after just one day, and the little ones will be swimming around after just a few days. Cardinal tetras are free-laying, so after the eggs are laid, remove the parents or they will eat the eggs. Young Paracheirodon axelrodi can be raised with slippers.
In the wild, the Cardinal Tetra lays eggs during the rainy season. Mating usually occurs at dusk. The male hugs the female, during the release of the eggs the male also releases his hom and fertilizes the eggs in the process. The up to 500 eggs are simply released into the river. Because the eggs of the Paracheirodon axelrodi are sensitive to light, they are released in the shaded parts of the river.