fish Demanding level

Paracheirodon axelrodi (Schultz 1956)

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Cardinal tetra

Paracheirodon axelrodi is a freshwater fish originally described from Rio Negro basin in Brazil. This species occurs mainly in shoals in the middle water layers of their habitat. They are usually present in streams and minor tributaries containing slow-moving water surrounded by thick, overhanging, riparian vegetation. The substrate is usually covered in fallen branches, tree roots, and leaf litter. The water is typically acidic, of a brownish colour due to the presence of substances released by decomposing organic matter.

Breeding in captivity is possible but difficult, and most specimens of Paracheirodon axelrodi that are present in the aquarium trade are caught in the tributaries of the Rio Negro and Orinoco. Anyway, this is one of the most popular and beautiful aquarium fishes.

Submitted by
Eleonora Pasquariello
0.2393390, -63.0959396
Geographical region
South America
Drainage Basin
Rio Amazonas
River catchment
Rio Negro
Water body type
Water body name
Water body part
Water body course
Upper course
Water body: tributary of
Tributary name
Type locality
Stream near Tomar, Rio Negro, near Porto Velho, Brazil.
Conservation status/IUCN Red List
Not Evaluated (NE)

Water Chemistry

Water information

Water type
Fresh water
Water color
Clear water
Water transparency
Concentration of sediments
Water temperature
23-27 °C
Water flow/curent

Chemical parameters

Dissolved Oxygen


Standard length
5 cm
Water volume (min. aquarium)
60 l
Social behaviour
Shoaling fish
Behaviour description

Paracheirodon axelrodi or cardinals is a generally peaceful species, an ideal mate in many biotope aquaria. It is best to kpep it with non-predatory, similarly-sized cichlids, characids, gasteropelecids, lebiasinids, smaller callichthyid or loricariid catfishes.

Aggression grade
Day active
Sexual dimorphism

Sexually mature females have a more rounded body and are a little larger than males.

Nutrition in Nature

Paracheirodon axelrodi is omnivorous. It usually feeds on worms, small crustaceans, filamentous algae, fallen fruit and suchlike.


Breeding tank set-up

Paracheirodon axelrodi is a shoaling fish. In the biotope aquarium, it is best to keep them in a group of 5 or more specimens. Breeding in captivity is possible but difficult.

This species seems to do best under fairly dim lighting. It is important to give the tank a natural feel, with aquatic plants (such as Pontederia, Cabomba, and floating Ceratopteris spp.), sandy substrate, driftwood roots, and branches. Also dried leaf litter would further emphasise the natural feel and provide a valuable secondary food source for fry. Furthermore, the humic substances released by the decaying leaves are beneficial for the water conditions, too.


Nutrition parents

In aquaria, cardinal tetra should be fed with dried foods but like most fishes it does best when given a varied diet that includes live and frozen food, such as chironomid larvae (bloodworm), mosquito larvae, DaphniaMoina, etc.

Mating type
Spawning behaviour

During spawing, it is best to set up another tank where to transfer the spawning individuals, in order to let the eggs hatch on the substrate and raise the fry. Eggs hatch in 24 to 30 hours and fry are free-swimming after 3 to 4 days.

The eggs and fry are sensitive to light in the early stages of life; so, the tank should be kept in darkness if possible.

Breeding habits
Egg scatterer
Hatching period
1-2 day
Number of eggs in average
Parental care
Fry number
Nutrition fry

Fry should be fed on infusoria-type food for the first few days, until they are large enough to accept microworm or brine shrimp nauplii.

Notes on reproduction