Paracheirodon axelrodi (Cardinal Tetra)

Background:

The Cardinal Tetra, Paracheirodon axelrodi, is a stunning freshwater fish native to the blackwater rivers of the Amazon Basin, particularly in Brazil, Colombia, and Venezuela. It is prized for its vivid coloration, featuring a bright iridescent blue stripe running along its body and a bold red stripe extending from the mid-body to the tail. Growing to about 3–5 cm, the Cardinal Tetra is larger and more vividly colored than its relative, the Neon Tetra. Its peaceful nature and schooling behavior make it a favorite for aquarists seeking a vibrant and harmonious community tank.

Care Requirements:

• Water Parameters:

  • Temperature: 23–27°C
  • pH: 4.5–6.5 (soft, acidic water preferred)
  • Hardness: 1–10 dGH

• Diet:
  Cardinal Tetras are omnivorous and thrive on a varied diet of high-quality micro pellets, flakes, and live or frozen foods like daphnia, brine shrimp, and bloodworms. Feeding them 1–2 times daily in small amounts supports their health and vibrant coloration.

• Tank Setup:
  A minimum tank size of 60 liters is recommended for a school of 10 or more, as they are highly social and display their best behavior in groups. Use a soft, dark substrate to enhance their iridescent colors. A densely planted tank with species such as Amazon swords, Java moss, and floating plants provides cover and mimics their natural blackwater habitat. Driftwood and leaf litter can be added to replicate tannin-rich waters. Subdued lighting enhances their vibrant coloration and reduces stress.

• Behavior:
  Cardinal Tetras are peaceful, schooling fish that occupy the mid-levels of the aquarium. They exhibit lively and synchronized swimming, creating a dazzling display when kept in large groups. They are shy when kept alone or in small numbers, so a group of 10 or more is essential for their well-being.

• Tank Mates:
  Ideal tank mates include other small, peaceful species such as Ember Tetras, Corydoras, and small Rasboras. They also coexist well with shrimp species like Amano or Cherry Shrimp. Avoid keeping them with larger, predatory fish, as their small size makes them potential prey.

Care Tips:

Cardinal Tetras thrive in stable, soft, acidic water conditions, so regular partial water changes and proper filtration are essential. Using driftwood or Indian almond leaves can help replicate their natural blackwater environment and stabilize water chemistry. Keep them in large schools to encourage natural behaviors and reduce stress. A varied diet with high-quality foods ensures optimal health and vibrant coloration.

The Cardinal Tetra is a dazzling centerpiece for any peaceful community aquarium. Its vivid colors, harmonious schooling behavior, and adaptability to well-maintained tanks make it a standout choice for both novice and experienced aquarists.