Cardinal tetra |1-2cms | Single

Cardinal Tetras (Paracheirodon axelrodi) are brightly colored freshwater fish that are popular among aquarists for their stunning appearance and peaceful nature. They are closely related to Neon Tetras but are slightly larger and display a more vivid red stripe that runs the entire length of their body. Native to the blackwater rivers and tributaries of the Amazon basin, these fish thrive in warm, soft, and acidic water, making them a favorite for planted tanks and biotope setups.
Key Characteristics of Cardinal Tetras:
Size: Grows up to 2 inches (5 cm) in length, slightly larger than Neon Tetras.
Color: Vibrant iridescent blue body with a bright red stripe extending from the nose to the tail.
Lifespan: Typically 4–5 years, though they can live longer with excellent care.
Behavior: Peaceful, schooling fish that prefer to be in groups of at least 6–8, with larger schools enhancing their natural behavior and reducing stress.
Activity: Active swimmers, usually occupying the middle levels of the tank.
Water Parameters for Cardinal Tetras:
Temperature: 23–27°C (73–81°F), warmer than Neon Tetras.
pH: 4.5–6.5, preferring soft and acidic water typical of blackwater habitats.
Hardness: Very soft water, 1–5 dGH.
Tank Size: A minimum of 15–20 gallons for a small school, with larger tanks preferred for bigger groups.
Tank Setup:
Substrate: Dark sand or fine gravel to mimic their natural habitat and enhance their colors.
Plants: Dense planting with species like Java fern, Amazon swords, and Vallisneria offers hiding spots and creates a natural environment.
Lighting: Moderate to dim lighting replicates their native shaded streams and enhances their iridescence.
Water Flow: Gentle water flow mimics the slow-moving streams they originate from.
Decor: Add driftwood, leaf litter, and stones to replicate blackwater conditions and create hiding spaces.
Diet:
Cardinal Tetras are omnivorous and require a varied diet:
Flakes & Pellets: High-quality micro-pellets or flakes as a staple diet.
Live/Frozen Foods: Brine shrimp, daphnia, bloodworms, and microworms provide essential protein.
Vegetable-Based Food: Spirulina-based flakes or finely chopped blanched vegetables like spinach can supplement their diet.
Tankmates for Cardinal Tetras:
These peaceful fish are ideal for community tanks with non-aggressive species:
Compatible Tankmates:
Other small tetras like Rummy-Nose Tetras or Ember Tetras.
Rasboras, guppies, and small peaceful barbs.
Bottom-dwellers like Corydoras, Kuhli Loaches, and Otocinclus.
Peaceful dwarf cichlids like Apistogramma.
Shrimp and small snails.
Avoid Aggressive Tankmates:
Large or aggressive fish like angelfish, Oscars, or large barbs.
Fin-nippers like tiger barbs.
Breeding Cardinal Tetras:
Breeding Cardinal Tetras in captivity is more challenging than Neon Tetras due to their specific water requirements:
Breeding Tank: Use a separate tank with very soft, acidic water (pH 4–6) and low lighting.
Spawning Setup: Add fine-leaved plants or spawning mops for egg-laying.
Pairing: Introduce healthy, well-conditioned males and females. Males are slimmer, while females are rounder, especially when carrying eggs.
Egg Care: After spawning, remove the adults to prevent egg predation.
Fry Care: Keep the tank dark, as eggs and fry are light-sensitive. Feed fry infusoria or liquid fry food until they grow large enough to eat crushed flakes or micro-pellets.
Differences Between Cardinal and Neon Tetras:
Feature
Cardinal Tetra
Neon Tetra
Size
Up to 2 inches
Up to 1.5 inches
Red Stripe
Extends the full length of body
Covers the rear half of the body
Preferred pH
4.5–6.5 (more acidic)
5.5–7.5 (neutral to slightly acidic)
Water Temperature
23–27°C (warmer)
20–26°C (cooler)
Care Considerations:
Stable Water Conditions: Cardinal Tetras are sensitive to changes in water parameters and prefer consistent, soft, acidic water.
Shoaling Needs: Keeping them in larger schools (10+) enhances their natural behavior and minimizes stress.
Disease Prevention: Regular water changes and avoiding overcrowding reduce the risk of common diseases like ich.
Conclusion:
Cardinal Tetras are an excellent choice for aquarists looking to add vibrant color and peaceful activity to their aquariums. Their shimmering appearance and compatibility with a variety of tankmates make them a staple in freshwater setups. With proper care, they will thrive and bring life to your tank for years.