Some ichthyologists believe fishkeepers should continue to support the sustainable cardinal fishery of the Amazon Basin, since thousands of people are employed in the region to capture fish for the aquarium trade.

The cardinal tetra has bright red ventral parts and an iridescent blue line that runs horizontally along its body.

The characteristic iridescence of this and related fishes, such as the neon tetra, is a structural color, caused by refraction of light within guanine crystals that develop within special cells called iridocytes in the subcutaneous layer.

[4] In the wild, the cardinal tetra swims upstream in large numbers to parts of its native river habitat completely enclosed above by rainforest canopy.

If the fishes are ready to spawn, the male pursues the female into fine-leaved plants; her fuller outline, which usually indicates the presence of ripe eggs within her reproductive tract, should be readily apparent at this point.

A study conducted in Manaus, Brazil, subjected cardinal tetras to adverse water conditions for 96 hours.

[5] An entire industry is in place in Barcelos on the banks of Brazil's Rio Negro in which the local population catches fish for the aquarium trade.

The local people may not become involved in potentially environmentally damaging activities, such as deforestation, because they can make a sustainable living from the fishery.