From Amazonia to the World: Biology, Cultivation, and Conservation of Cardinal Tetra ( <i>Paracheirodon axelrodi</i> )

The South American cardinal tetra, Paracheirodon axelrodi, is one of the most intensively commercialized freshwater ornamental fish worldwide. Global exports for this species are estimated at 30 million individuals annually, with the high demand supplied through both wild collection within its native range of Brazil and Colombia, and captive production largely by the Czech Republic and to a lesser but increasing extent in Southeast Asian countries (including Indonesia, Malaysia, and Vietnam). With monitoring indicating the core cardinal tetra population is not impacted by current harvest practices, no restrictions have been placed on the wild fishery, in contrast to many other ornamental fish taxa. Captive production of the cardinal tetra currently has a total volume comparable to that of the fishery. If the conditions in the species’ native range change—whether policy, economics, or environment—captive production is positioned to increase in importance. In extreme circumstances, aquaculture can serve as a haven if cardinal tetras become imperiled, securing the supply to the ornamental market without excessive pressure on the wild populations. As a proactive step, a detailed species guide for rearing the cardinal tetra in captivity is presented in this review. This work is based on a literature review, experience of breeders in both the Czech Republic and Asia, and on controlled experiments performed to validate the effects of water conditioning on spawning success. The minimal carbonate (temporary) hardness of water was identified as the most important factor affecting the success of cardinal tetra reproduction in captivity. This insight into history, biology, exploitation, and conservation of this iconic ornamental fish provides a proactive basis for future responsible and sustainable activities and management of this charismatic and iconic ornamental fish.