Cardinal Tetra
Paracheirodon axelrodi · Peaceful · Intermediate care
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A dazzling nano shoaling fish with an electric-blue neon line and deep red running the full length of its body. Peaceful, hardy in soft acidic water and stunning in a well-planted community aquarium kept in a group of eight or more.
At a glance
Species profile Paracheirodon axelrodi
Origin
Upper Rio Negro and Orinoco river basins, South America
Family
Characidae
Adult size
Up to 5 cm
Diet
Micro-omnivore: quality micro pellets and flakes plus small frozen or live daphnia, cyclops and baby brine shrimp (Omnivore (micropredator))
Temperament
Peaceful
Swimming level
Middle
Minimum group
8+ (shoaling)
Lifespan
4–5 years with good care
Minimum tank
60 L / 60 cm long minimum for a shoal
Water type
Freshwater
Size to scale
5 cm adult length, shown to scale against an iPhone 15 Pro (14.66 cm).
Natural range
Where it comes from — South America
Upper Rio Negro and Orinoco river basins, South America
Water
Singapore tap water vs its needs
Hardness: Soft, 1–8 dGH preferred.
In the aquarium
How it lives in the tank
Swims in the middle of the tank
Keep in a group of 8+
Sensitivity Index — Moderate
Adaptable, but happiest with stable parameters in a matured tank.
Our own read on how forgiving this species is of water changes — not a formal standard.
Keeping & care
What this fish needs
Family
About the Characidae family
Characidae (the characins or tetras) is a large, diverse family of small freshwater fishes native to the Americas, with most aquarium species coming from tropical South America (the Amazon and Orinoco basins and surrounding waters). Typical members are small, active, silvery to brightly coloured shoaling fishes with a small adipose fin between the dorsal and tail; well-known examples include the neon and cardinal tetra, black skirt, serpae, and rummy-nose tetras. Most kept species are peaceful, hardy schooling fish that do best in groups and suit soft, slightly acidic to neutral, well-planted tanks, though a few (such as some serpae and skirt tetras) can be fin-nippy.
Keep tetras in a shoal of at least six (more is better) in a mature, planted tank with soft, slightly acidic to neutral water and gentle flow; the group calms them, brings out their colour, and reduces any fin-nipping.
Breeding
Egg-scattererMost aquarium tetras are egg-scattering spawners that give no parental care and readily eat their own eggs. Breeders typically condition a pair or group on live foods, then move them to a dim, soft, slightly acidic spawning tank with fine-leaved plants or a spawning mop and a mesh or marble bottom; spawning is often triggered by the morning light, after which the parents are removed. Eggs are light-sensitive and usually hatch in about a day, with the tiny free-swimming fry needing infusoria or similarly small first foods before graduating to baby brine shrimp.
Feeding
Recommended food
Compatibility
Best tankmates
Community
