Cardinal Tetra

The Cardinal Tetra (Paracheirodon axelrodi) is a small and vibrant freshwater fish that originates from South America. With its stunning red and blue colors, it has become one of the most popular species of aquarium fish. In this article, we will dive into the details of the Cardinal Tetra, including its appearance, natural habitat, behavior, reproduction, life span, diet, and how to care for them in a home aquarium.


The Cardinal Tetra is a small fish that grows to an average size of 4 cm (1.5 inches) in length. Its body is slender and has a striking translucent blue coloration with a shimmering metallic look. Another feature of this fish is the bright red coloration on its mid-section and fins. These colors are brightest in adult males, while the females are generally less colorful. The neon stripe of the Cardinal Tetra becomes iridescent because of external lighting. The color changes between blue and green depending on the angle of the light.

Natural environment

The Cardinal Tetra is native to the tributaries of the Amazon Basin and the Orinoco and Negro rivers in South America, specifically in Brazil and Guyana. These areas have warm water temperatures of 22-28 °C (72-82 °F), low light levels, and plenty of hiding places provided by the dense vegetation.


The Cardinal Tetra is a shoaling species, meaning that it prefers to live in groups. In the wild, they can form large schools, even into the hundreds, swimming and feeding as one unit as a protection against predators. In the aquarium, they should be kept in groups of at least six individuals. They are peaceful fish and will generally not cause any trouble with other species in the aquarium. However, they can be shy, so be sure to provide plenty of hiding places and a well-planted environment to help them feel comfortable.

Reproduction & life span

Cardinal Tetra are egg-layers, and the eggs will hatch in about 24-48 hours. The females release their eggs during the rainy season. The adult life span of the Cardinal Tetra is approximately 5 years with proper care. Most Cardinal Tetras in the aquarium trade come from the wild. There are tank-bred Cardinals but not many, as they are hard to breed.


The Cardinal Tetra is an omnivorous species and in the wild, they feed on small insects, crustaceans, and other small invertebrates. In the aquarium, they will eat a variety of foods, including live or frozen foods, flake food, and pellets. It is important to provide a balanced diet to maintain the health of the fish.

Keeping a Cardinal Tetra

The Cardinal Tetra is a relatively hardy species and is easy to care for in the home aquarium. They prefer a well-planted environment with plenty of hiding places, and a temperature of 22-28 °C (72-82 °F). The pH has to stay slightly acidic like in their natural environment, it is recommended to keep between 4.5 to 6.5. Though Cardinals can tolerate a pH of up to 7.5, it is best to make sure it stays below 6.5 and a water hardness between 4-8°d GH. Be sure to provide a filtration system and maintain a weekly water change routine to keep the water quality high.

In conclusion, the Cardinal Tetra is a beautiful and hardy species that makes a great addition to any aquarium. With proper care, they can live for up to 5 years, but there are some reports of them reaching up to 10 years in captivity. They will provide a stunning display of colors in your home aquarium. If you are considering adding Cardinal Tetras to your aquarium, be sure to provide a suitable environment and a balanced diet to help them thrive.

Scientific nameParacheirodon axelrodi
Type of aquariumFreshwater
Size4 cm / 1.5 inches
RegionSouth America
Ideal tank sizeAt least 40 liters / 10 gallons per 6 fish, more is recommended
Ideal water temperature22-28 °C / 72-82 °F
pH4.5 – 6.5
DietOmnivorous: live or frozen foods, flake food, and pellets
SchoolingYes, keep at least 6 together



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