Paracheirodon axelrodi (Schultz 1956)

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

GPS: 0.2393390, -63.0959396

Geographical region: South America
Drainage Basin: Rio Amazonas
River catchment: Rio Negro
Water body type: River
Water body name: Preto
Water body part
Water body course: Upper course
Water body: tributary of: Rio
Tributary name: Aracà

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: Low
Concentration of sediments: Medium
Water temperature: 23-27 °C
Water flow/curent: Slow

Chemical parameters

pH: 4-6
Conductivity
GH
KH
Dissolved Oxygen

Biology

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

Peacefull

Activity

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.

Reproduction

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, Daphnia, Moina, 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