A stunning schooling fish native to the upper Orinoco and Rio Negro basins in South America. Famous for its brilliant iridescent blue line and a vivid red stripe that extends the full length of its body (distinguishing it from the Neon Tetra). They are strictly schooling fish that thrive in warm, acidic blackwater environments.
At a Glance
Tank Requirements
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Water Parameters
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Temperament & Compatibility
Available Varieties
Each variety inherits the species defaults above. Only differences are highlighted.
Standard
The standard wild-type Cardinal Tetra. Needs to be kept in a group of at least 6 (preferably 10+) to feel secure and exhibit natural schooling behavior. Dim lighting or tannin-stained water brings out their best colors.
Differs in 1 trait from base species
Also known as: Wild Type
Albino / Gold
A selectively bred morph that lacks dark pigmentation. The body appears pinkish-gold, but they retain the distinctive iridescent blue and red stripes. Husbandry is identical to the standard form.
Differs in 1 trait from base species
Also known as: Gold Cardinal, Albino Cardinal
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🟢Ideal Tank MatesCardinal Tetra Care Guide Summary
The Cardinal Tetra, scientifically known as Paracheirodon axelrodi, belongs to the Characins family group. Adults reach a maximum size of approximately 4 cm and have a fusiform body shape with a moderate growth rate. Classified as peaceful, this species primarily occupies the mid-level zone of the aquarium and produces a low level of biological waste.
To thrive, the Cardinal Tetra requires a freshwater only aquarium with a minimum volume of 55 litres and a tank length of at least 60 cm. Water temperature should be maintained between 24°C and 29°C, with a pH range of 4–7 and a general hardness of 1–8 dGH. A low water flow is preferred. An aquarium test kit can help you monitor these values.
Due to its specialist needs, the Cardinal Tetra is best suited for fishkeepers who can provide a carefully planned setup. This species is available in 2 varieties: Standard and Albino / Gold. Each may differ slightly in size, temperament, or care needs, so it is worth checking the specific requirements of the variety you plan to keep.
Cardinal Tetra Habitat Setup
When setting up an aquarium for the Cardinal Tetra, a low water flow best suits their natural preferences. Because this species occupies the mid-level zone, the aquarium layout should prioritise open swimming space in the centre of the tank for free movement. Useful additions include driftwood, which can serve as both a hiding place and a dietary supplement, leaf litter or blackwater tannins to replicate their natural soft-water habitat, and dense planting to provide cover, break sightlines, and reduce stress.
Cardinal Tetra Compatibility Notes
Classified as peaceful, the Cardinal Tetra is a schooling species that feels most secure in a sizeable group, where natural shoaling behaviour reduces stress and brings out their best colours. Selecting tankmates that favour different water layers from the mid-level zone can help reduce competition and territorial overlap.
Recommended Tank Sizes
Standard aquarium sizes that meet the minimum volume and length requirements for Cardinal Tetra.
15 Gallon Standard
20 Gallon High
20 Gallon Long
29 Gallon Standard
30 Gallon Breeder
36 Gallon Bowfront
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Frequently Asked Questions About Cardinal Tetra
How big does Cardinal Tetra get?
Cardinal Tetra (Paracheirodon axelrodi) typically reaches a maximum adult size of approximately 4 cm. They have a fusiform body shape and a moderate growth rate.
What tank size does Cardinal Tetra need?
A minimum aquarium volume of 55 litres and a tank length of at least 60 cm are recommended for Cardinal Tetra. This ensures enough swimming space and helps maintain stable water conditions.
What water parameters does Cardinal Tetra need?
Cardinal Tetra thrives in freshwater only conditions with a temperature range of 24–29°C, a pH between 4 and 7, and a general hardness of 1–8 dGH. A low water flow is preferred.
Is Cardinal Tetra peaceful or aggressive?
Cardinal Tetra is classified as peaceful with an aggression score of 1 out of 10. They are generally well-suited to peaceful community tanks.
How many Cardinal Tetra should be kept together?
Cardinal Tetra is a schooling species and should be kept in groups of at least 6. Larger groups help distribute aggression and encourage natural schooling behaviour.
Does Cardinal Tetra have any special tank requirements?
Yes. Cardinal Tetra benefits from leaf litter/blackwater, driftwood (digestion/hiding), and plants - densely covered in the aquarium. These features help replicate their natural habitat and promote overall health and well-being.
Similar Species
Neon Tetra
Paracheirodon innesi
One of the most iconic freshwater fish in the hobby, famous for its striking iridescent blue and red stripes. Originally from the blackwater streams of the Amazon basin, they prefer slightly cooler water than many tropical fish and must be kept in schools to thrive, display natural behaviors, and feel secure.
Emperor Tetra
Nematobrycon palmeri
A striking, robust schooling fish from Colombia. Unlike many tetras, they do not swim in a tight shoal, preferring to loosely associate while males stake out small territories to display to females. They feature a bold black lateral line and iridescent purple/blue hues.
Black Neon Tetra
Hyphessobrycon herbertaxelrodi
A peaceful, active schooling fish native to the Paraguay basin. Known for its striking contrast of a dark black lateral stripe underneath a glowing iridescent white/green-gold stripe. Excellent for community aquariums, particularly in planted setups or blackwater biotope tanks with subdued lighting.
Glowlight Tetra
Hemigrammus erythrozonus
A peaceful, schooling nano fish native to the Essequibo River basin in South America. They are famous for their translucent bodies and the striking iridescent neon-orange stripe running from snout to tail. They thrive in mature, planted aquariums with slightly soft, acidic water and subdued lighting.
Congo Tetra
Phenacogrammus interruptus
A stunning, large schooling fish native to the Congo River basin. Known for their iridescent rainbow colors and active swimming behavior. Despite their size, they are notoriously peaceful and can be skittish, requiring ample swimming space, dim lighting or floating plants, and peaceful tank mates. Avoid keeping with fin-nippers.
Diamond Tetra
Moenkhausia pittieri
A stunning, deep-bodied tetra endemic to Lake Valencia in Venezuela. Named for the brilliant, iridescent scales on its flanks that sparkle like diamonds under the right lighting. They are highly active, peaceful schooling fish that thrive in well-planted aquariums. Males develop spectacular, flowing fins as they mature.