Cardinal Tetra care guide
Cardinal Tetra (Paracheirodon axelrodi) — minimum tank 40 L, temperature 24-28 °C, pH 4.5-7. Peaceful middle-water species.
Compiled by Aquairi from published sources · Published · Updated
Overview
The Cardinal Tetra (Paracheirodon axelrodi) is a small characid with an iridescent blue lateral line and a continuous deep-red band extending the full length of the lower body. It is closely related to the Neon Tetra but the red coloration covers a noticeably greater portion of the body.
Taxonomy
- Family: Characidae
- Genus: Paracheirodon
- Scientific name: Paracheirodon axelrodi
- Common synonyms: Red Neon Tetra
Habitat
Native to the upper Orinoco and upper Rio Negro drainages in Colombia, Venezuela and Brazil. It inhabits shaded, slow-moving blackwater rivers and inundated forest where humic acids stain the water and reduce mineral content. Leaf litter and submerged branches dominate the substrate.
Tank requirements
- Minimum tank volume: 40 L (10.6 US gal)
- Adult size: 3-5 cm
- Temperature: 24-28 °C (75-82 °F)
- pH: 4.5-7
- GH: 1-8 °dGH
- Water flow: low
- Lifespan: 3-5 years
- School size: ≥6 individuals
Diet
Cardinal Tetras are micropredators. Studies of wild specimens record a diet of chironomid larvae, microcrustaceans (water fleas, copepods), insect eggs, rotifers and testate amoebae picked from leaf litter and vegetation. In aquaria they readily accept micro-pellets, crushed flakes and small frozen foods.
Compatibility
A peaceful schooling species suited to soft-water community tanks. Keep groups of at least six. Compatible with Neon Tetra, Rummy-nose Tetra, Corydoras, Otocinclus and other small soft-water community species. Avoid keeping with adult Angelfish, Oscar or other large predators.
Breeding
Breeding is considered difficult. It requires very soft, acidic water (GH 1-2, pH 5.0-6.0) and dim light. Spawning takes place among fine-leaved plants where eggs and milt are released simultaneously. Eggs are highly sensitive to fungal infection and ultraviolet light; the spawning tank must be kept dark until the fry are free-swimming.
Conservation status
IUCN Red List: Least Concern. A large share of fish in the international trade are wild-caught in Brazil under regulated fisheries; captive-bred specimens are also widely available.
Breeding Cardinal Tetra
Overview
The Cardinal Tetra (Paracheirodon axelrodi) is an egg-scattering characin whose captive breeding is rated advanced. It was historically difficult to breed in captivity, although many breeders now produce the species by mimicking its natural blackwater conditions.
Sexing
Females are noticeably rounder-bodied and slightly larger than males, an outline that becomes apparent when ripe eggs are present in the reproductive tract. Males have very flat, almost straight-line bellies.
Conditioning the Breeders
Condition the fish on plenty of small live foods. For group spawning use about half a dozen specimens of each sex; for pair spawning select the fattest female and best-coloured male.
Breeding Setup
- Light: very dimly lit; eggs and fry are light-sensitive in the early stages
- Water: pH 5.5-6.5, hardness around 1-5 (very soft, acidic)
- Temperature: 24-29 °C (about 80-84 °F)
- Spawning medium: fine-leaved plants such as java moss, spawning mops, or a mesh base eggs fall through
- Filtration: a small air-powered sponge filter bubbling gently
Spawning Behavior & Trigger
The male pursues the female into fine-leaved plants and the pair release eggs and sperm together. Spawning tends to occur during the night, often around midnight, and has been observed even with the aquarium lights on, the fish retaining their night-time colour pattern.
Egg & Fry Care
Eggs hatch in 24-36 hours and the fry become free-swimming 3-4 days later. Keep the tank dark because the eggs and fry are light-sensitive early in life. First foods are an infusoria-type food, progressing to microworm or brine shrimp nauplii as the fry grow.
Common Challenges
The species demands very soft, acidic water for fertilisation, and the light-sensitive eggs require darkness. Recreating the shaded, tannin-rich blackwater of its natural streams is the key to consistent success.