Cardinal Tetra: Fish Species Profile

The cardinal tetra (Paracheirodon axelrodi) is a vibrant freshwater fish renowned for its striking red and blue coloration. Native to South America’s Amazon Basin, particularly the Rio Negro and Orinoco Rivers, this species is a favorite among aquarists for its peaceful demeanor and schooling behavior.

Species Overview

• Common Names: Cardinal tetra, red neon tetra
• Scientific Name: Paracheirodon axelrodi
• Adult Size: Up to 2 inches (5 cm)
• Life Expectancy: 4 to 5 years

Characteristics

• Family: Characidae
• Origin: South America (Brazil, Colombia, Venezuela)
• Social: Peaceful, schooling
• Tank Level: Midwater
• Minimum Tank Size: 20 gallons
• Diet: Omnivore
• Breeding: Egglayer; challenging in captivity
• Care Level: Intermediate
• pH: 4.6 to 6.2
• Hardness: Up to 4 dGH
• Temperature: 73–81°F (23–27°C)

Origin and Distribution

Cardinal tetras inhabit the upper Orinoco and Rio Negro rivers in South America. They thrive in slow-moving, tannin-rich blackwater streams and tributaries, environments characterized by soft, acidic water and dense vegetation.

Colors and Markings

This species boasts a vivid red stripe running along the lower half of its body, complemented by an iridescent blue stripe above. The combination of these colors makes the cardinal tetra one of the most visually striking freshwater fish.

Tankmates

Cardinal tetras are peaceful and do well in community tanks with other non-aggressive species. Suitable tankmates include:

• Other small tetras (e.g., neon tetras)
• Rasboras
• Danios
• Dwarf gouramis
• Corydoras catfish

Avoid housing them with larger fish that might view them as prey.

Habitat and Care

To replicate their natural habitat:

• Tank Setup: Provide a well-planted aquarium with open swimming areas. Incorporate driftwood and leaf litter to simulate blackwater conditions.
• Water Parameters: Maintain soft, acidic water with stable conditions. Regular water changes are essential, as cardinal tetras are sensitive to fluctuations.
• Lighting: Subdued lighting is preferred, which can be achieved with floating plants.

Diet and Feeding

Cardinal tetras are omnivorous and thrive on a varied diet:

• High-quality flake or micro-pellet food
• Live or frozen foods such as brine shrimp, daphnia, and bloodworms

Feed small portions multiple times daily, ensuring they consume the food within a few minutes.

Gender Differences

Males are generally slimmer with a more intense coloration, while females have a rounder belly, especially when carrying eggs.

Breeding

Breeding cardinal tetras in captivity is challenging:

• Breeding Tank: Set up a separate tank with very soft, acidic water (pH around 5.0) and temperatures between 80–82°F (27–28°C).
• Spawning: Provide fine-leaved plants or spawning mops. After spawning, remove adults to prevent egg predation.
• Raising Fry: Feed fry infusoria or commercially prepared fry food until they can accept larger foods.

Further Research

For those interested in similar species, consider exploring:

• Neon tetra (Paracheirodon innesi)
• Rummy-nose tetra (Hemigrammus rhodostomus)
• Ember tetra (Hyphessobrycon amandae)

These species share comparable care requirements and can coexist harmoniously in a community aquarium.

FAQ

• How many cardinal tetras should be kept together? It’s best to keep them in groups of at least six to promote natural schooling behavior and reduce stress.
• Are cardinal tetras hard to keep? They require stable water conditions and are sensitive to changes, making them more suitable for aquarists with some experience.
• What’s the difference between cardinal tetras and neon tetras? While both have blue and red stripes, the cardinal tetra’s red stripe extends the full length of its body, whereas the neon tetra’s red stripe only reaches halfway.