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Cardinal Tetra

By The Aquarium Calculators Editorial Team ·

Paracheirodon axelrodi

Complete Cardinal Tetra care guide covering omnivore diet requirements, peaceful temperament, minimum 10 Gallons tank setup, and compatible freshwater tankmates. Difficulty: Easy.

Cardinal Tetra

Quick Answer

Cardinal Tetra (Paracheirodon axelrodi) is a captivating and highly sought-after freshwater species. It requires a minimum 10 Gallons aquarium with a pH of 6.0 - 7.2 and temperature range of 22-26°C. This omnivore occupies the middle zone and makes an excellent addition to community setups.

Intro

Cardinal Tetra (Paracheirodon axelrodi) is a captivating and highly sought-after freshwater species. Known for their peaceful nature and distinct appearance, they occupy the middle levels of the aquarium and bring dynamic energy to any setup.

Setup

Cardinal Tetra requires a stable, well-filtered aquarium of at least 10 gallons. They thrive best with moderate water movement and a reliable heater to maintain temperatures around 22-26°C. Ensure pH levels remain consistent between 6.0 - 7.2 to prevent stress and support long-term health.

Feeding

As a omnivore, the Cardinal Tetra is not a picky eater. They should be fed a high-quality base of flakes, sinking pellets, or wafers. Periodic supplementation with frozen or live foods, such as bloodworms or brine shrimp, will boost their health and colors.

Compatibility

Cardinal Tetra has a peaceful temperament. They are schooling fish and MUST be kept in a group of at least 6 individuals to exhibit natural schooling behavior and reduce stress. Avoid placing them with aggressive species or tankmates they are listed as incompatible with, such as: None.

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Tank Position
Middle
Water Temp
22-26°C
Adult Size
See profile
Water pH
6.0 - 7.2

Species Characteristics

Adult Size
Lifespan
Growth Rate
moderate
Tank Compatibility
Community compatible
Indoor Aquarium
Yes

Water Parameters

Water Temperature
Humidity
Water pH

Tank Lighting

Tank Lighting
Standard lighting
Light Hours
N/A
Intensity
moderate

Feeding & Diet

Diet Type
Diet: Omnivore
Feeding Schedule
N/A
Live Food Options
N/A

Frequently Asked Questions

How many Cardinal Tetras should be kept together?
Maintain a minimum school of 12 to 15 individuals in a tank of at least 20 gallons (75 liters) with a footprint of 24x12 inches (60x30 cm). Cardinal tetras (Paracheirodon axelrodi) are tight-schooling fish that display their vivid blue and red stripes optimally in groups of 20+. Groups under 8 cause chronic stress, faded colors, and susceptibility to disease. Provide dim lighting, dark substrate, and floating plants to enhance coloration. Avoid large tank mates (angelfish, discus) that will prey on them. Tank length should exceed 24 inches (60 cm) for natural shoaling.
What are the precise water parameters for Cardinal Tetras?
Target pH 5.5 - 6.5 (optimal 6.0), General Hardness 2 - 6 dGH, Carbonate Hardness 1 - 4 dKH, Total Dissolved Solids 40 - 120 ppm, Electrical Conductivity 80 - 240 μS/cm, and temperature 73°F - 82°F (23°C - 28°C). They require soft, acidic, blackwater conditions; hard water (dGH >10) causes kidney failure and shortened lifespan. Maintain nitrates below 10 ppm with weekly 25% water changes using RO water. Add Indian almond leaves (1 per 5 gallons) and peat filtration. Avoid alkaline substrates. pH must be stable; fluctuations >0.2 cause shock.
What is the nutritional and medication protocol for Cardinal Tetras?
They are omnivores requiring 35% protein, 10% fat, 55% plant matter. Feed high-quality micro-pellets or crushed flakes twice daily, supplemented with frozen daphnia, baby brine shrimp, cyclops, and bloodworms. Offer spirulina flakes weekly. They have tiny mouths; ensure food particle size under 0.5 mm. Medication alert: Sensitive to copper (0.15 mg/L max) and formalin. Use malachite green at half-dose (0.025 mg/L) for ich. Praziquantel is safe. Avoid salt (tolerance <3 ppt). Quarantine with methylene blue. They are susceptible to neon tetra disease; remove infected fish immediately.
How to breed Cardinal Tetras in captivity?
Breeding is challenging and requires soft, acidic water. Condition 10-15 mature fish (1.5 years old) with live baby brine shrimp and blackworms for 4 weeks. Set up a 10-gallon (38 liter) breeding tank with 3 inches (7.5 cm) of RO water (pH 5.5, 1 dGH, 80°F/27°C), a spawning mop, and very dim light (cover sides). Simulate dawn with a single 1-watt LED. Spawning occurs in absolute darkness; female releases 300-500 eggs. Remove parents after 6 hours. Eggs hatch in 24-30 hours. Fry are light-sensitive; keep tank covered. Feed infusoria for 5 days, then microworms, then baby brine shrimp.