Кардинал тетрасы: сипаттамасы және өмір сүру ортасы

Species of fish
Speciesbox
| name = Cardinal tetra
| image = Cardinal Paracheirodon axelrodi (3). jpg
| status = LC
| status system = IUCN3.1
| status ref =
| taxon = Paracheirodon axelrodi
| authority = (L. P. Schultz, 1956)
| synonyms =
| synonyms ref =

American ichthyologist Leonard Peter Schultz described the cardinal tetra in 1956 as Cheirodon axelrodi. The specific epithet honors ichthyologist Herbert R. Axelrod. Hyphessobrycon cardinalis is an obsolete synonym. The fish's common name, cardinal tetra, refers to the brilliant red coloration, reminiscent of a cardinal's robes. P. axelrodi is also often called the red neon tetra. The species exists in a number of different color forms or phenotypes. A "gold" and "silver blonde" form exists in the Rio Negro drainage that 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 that stops posterior to the adipose. The Orinoco phenotype may represent a subspecies of P. axelrodi.

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. The exact shade of blue seen depends on the viewing angle of the viewer relative to the fish if the viewpoint changes so as to look at the fish more from below, the colour will change hue, becoming more deeply sapphire blue and even indigo. Change of viewpoint to one above the fishes, however, and the color becomes more greenish. Cardinal tetras appear to grow larger in captivity than they do in the wild.

In the wild, the cardinal tetra swims upstream in large numbers to parts of its native river habitat completely enclosed above by rainforest canopy. Such waters are subject to heavy shading by the rainforest trees, and virtually no sunlight reaches them. Here, the fishes spawn in large aggregations. 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. If the female is ready, she allows the male to swim alongside her, and together, the pair release eggs and sperm.

The fish might also be effectively an annual species with a lifespan of just a single year in nature. It lives for several years in captivity. For those seeking to breed them in the aquarium, the best way to do so is by mimicking the same natural setup. A study conducted in Manaus, Brazil, subjected cardinal tetras to adverse water conditions for 96 hours. The fish perished at a low temperature of and a high of , and pH below 2.9 or above 8.8.

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 cardinal fishery here is highly valued by the local people who act as stewards for the environment. 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.