Cardinal Tetra - Aquarium Maintenance

Aquarium Maintenance

Given the origins of the cardinal tetra, namely blackwater rivers whose chemistry is characterised by an acidic pH, low mineral content and the presence of humic acids, the species is adaptable to a wide range of conditions in captivity, though deviation from the soft, acidic water chemistry of their native range will impact severely upon breeding and fecundity. The preferred temperature range of the fish is 21°C to 28°C (70°F to 82°F). The water chemistry of the aquarium water should match that of the wild habitat - filtration of the aquarium water over peat is one means of achieving this.

As the species is a shoaling species in the wild, groups of six or more individuals should be maintained in an aquarium. They will shoal with their close cousins neon tetras, though, so a combination of these two species totalling at least six should suffice. Tank currents can help encourage shoaling behavior. The larger the numbers present in an aquarium (subject to the usual constraints imposed by space and filtration efficiency), the better, and large shoals in any case form an impressive and visually stunning display.

The species will feed on a wide range of aquarium foods, though again, conditioning fishes of this species for breeding will usually require the use of live foods such as Daphnia.

Aquarium furnishings should be planned with some care. Live aquatic plants, as well as providing additional biological filtration components to assist with nitrate management, provide an environment that resembles at least part of the wild habitat, and fine-leaved plants such as Cabomba are usually the plants of choice, though other plants such as Amazon swordplants and Vallisneria are equally suitable for an aquarium housing them. Floating plants providing shade will also be welcomed by the species; this is connected with the breeding of the fish. A perfect biotope to promote breeding would be bogwood, a few live native plants, dark substrate and subdued lighting with floating plants.

The species exists in a number of different color forms or phenotypes. A "gold" and "silver-blonde" form exist in the Rio Negro drainage which has less blue in the longitudinal stripe. The normal form from the Rio Negro drainage has a blue stripe which extends to the adipose fin, while the Orinoco drainage phenotype has a stripe which stops posterior to the adipose. The Orinoco phenotype may represent a subspecies of P. axelrodi.